An Australian plane searching for missing flight MH370 has spotted two further objects in the southern Indian Ocean search area, adding to earlier possible debris sightings from a Chinese crew.
According to a statement issued by the Australian Maritime Safety Authority (Amsa), "a grey or green circular object and an orange rectangular object" were located by an Australian air force Orion aircraft.
Amsa said that one of its ships, the HMAS Success, was also now on the scene, and that the objects were within the search area being scoured today.
Earlier on Monday spotters on a Chinese plane said they had spotted two white, square-shaped objects in the southern Indian Ocean, at that stage the second possible sighting of plane debris made with the naked eye in the search for the missing Malaysia Airlines Boeing 777.
Spotters aboard that search plane reported the coordinates to a Chinese icebreaker ship, Xue Long, which was making its way to the area - as well as to the central Australian command centre.
In addition to the two larger floating objects, the searchers also report seeing a range of smaller, white debris scattered over several square miles, according to China's Xinhua news agency.
The sightings were all made in the area identified in previous satellite images from Australia and China.
The developments came as the US prepared to send a specialised device that can locate black boxes into the region.
The US Pacific command said the Towed Pinger Locator, which is pulled behind a vessel at slow speeds, has highly sensitive listening capability so that if the wreck site is located, it can hear the black box pinger down to a depth of about 20,000 feet.
Commander Chris Budde, a US Seventh Fleet operations officer, said: "This movement is simply a prudent effort to preposition equipment and trained personnel closer to the search area so that if debris is found we will be able to respond as quickly as possible since the battery life of the black box's pinger is limited."
The two Chinese planes joining the search today increased the number of aircraft to 10 from eight a day earlier.
An Australian plane scouring the search area spotted a wooden pallet and other objects late on Saturday, including what looked like variously coloured straps or belts. However, it was unable to get up close or take photographs, and other aircraft dispatched to the site on Sunday could only see seaweed.
The Australian Maritime Safety Authority's rescue co-ordination centre said the weather in the area, about 2,500 (1,550 miles) from Perth, was expected to deteriorate with rain likely.
Australian transport minister Warren Truss said "nothing of note" was found yesterday, which he described as a "fruitless day".
"It's going to be a challenge, but we'll stick at it," he told Australian Broadcasting Corporation radio before the first aircraft left Perth at dawn.
"We're just, I guess, clutching at whatever little piece of information comes along to try and find a place where we might be able to concentrate the efforts."
A cyclone bearing down on the Australian north-west coast "could stir up less favourable weather," he said.
Flight 370 vanished while en route from Kuala Lumpur, Malaysia, to Beijing, setting off a multinational search that has turned up no confirmed pieces and nothing conclusive on what happened to the jet.
The southern Indian Ocean is thought to be a potential area to find the jet because Malaysian authorities have said pings sent by the Boeing 777-200 for several hours after it disappeared indicated that the plane ended up in one of two huge arcs.
One is a northern corridor stretching from Malaysia to Central Asia, and the other a southern corridor that stretches toward Antarctica.
Malaysian authorities have not ruled out any possible explanation for what happened to the jet, but have said the evidence so far suggests it was deliberately turned back across Malaysia to the Strait of Malacca, with its communications systems disabled. They are unsure what happened next.
Authorities are considering the possibilities of hijacking, sabotage, terrorism or issues related to the mental health of the pilots or someone else on board.
In the US, Tony Blinken, President Barack Obama's deputy national security adviser, said on CNN: "There is no prevailing theory."
"Publicly or privately, we don't know," he said. "We're chasing down every theory."
Royal Navy ship sent to help search
Britain has tasked survey vessel HMS Echo to help with the operation - but it will not arrive for several days.
Prime Minister David Cameron's spokesman said the Government stood ready to provide any other assistance requested.
"The exact role (HMS Echo) will play will depend on the status and the nature of the investigation by the time it arrives in that area," he said.
"That is currently the assistance that's being provided, but we stay in close touch with the Malaysian authorities and if there's more to do that the British Government can do then we will, of course, look upon that very constructively."
HMS Echo is a multi-role survey ship commissioned by the Royal Navy to carry out a wide range of work.
Built in 2002 in Devon, it can provide support to submarine and amphibious operations by collecting ocean data and has a range of 9,000 nautical miles.
It is equipped with a survey motor boat, called Sapphire, which is capable of operating independently and supporting a small group of surveyors who can live and work ashore to carry out surveys.
The ship can support mine warfare, possesses an array of weapons and carries a small detachment of Royal Marines.
It has previously been deployed to the Red Sea, the Gulf, the Indian Ocean, the Middle and Far East.
Confusion in search for MH370: A timeline
Uncertainty and frustration has clouded the mystery over the search for the missing Malaysian Airlines flight MH370.
A series of false leads has added to wide-ranging speculation that pilot error, plane malfunction, hijacking or terrorism may have been the cause.
March 8 - Malaysian Airlines flight MH370 takes off from Kuala Lumpur at 12.41am local time bound for Beijing carrying 227 passengers and 12 crew.
Someone, apparently the co-pilot, makes the final voice communication from the cockpit at 01.19am, saying "All right, good night" to air traffic controllers.
The plane is last seen on military radar at 02.14am heading west over the Strait of Malacca. Half an hour later the airline reveals to the public it has lost contact with the plane. The plane was due to land around 6.30am.
Officials reveal two passports used to board the flight were stolen, raising the first suspicions of terrorist involvement.
March 9 - Malaysia's air force chief says that military radar indicated the missing Boeing 777 jet may have turned back.
March 10 - Vietnamese aircraft search for a plane door spotted in their waters but find nothing.
March 11 - The hunt is widened to cover a 115-nautical mile radius involving 34 aircraft and 40 ships from several countries.
The Malaysian military claims it has radar evidence showing that the missing plane changed course and made it to the Malacca Strait which is hundreds of miles away from the last location reported by civilian authorities. The aircraft was believed to be flying low.
The two male passengers travelling with stolen passports were Iranians who had bought tickets to Europe and were probably not terrorists, Malaysian police said.
March 12 - Satellite images on a Chinese government website shows suspected debris from the missing plane floating off the southern tip of Vietnam, China's Xinhua News Agency says.
The report includes co-ordinates of a location in the sea off the southern tip of Vietnam and east of Malaysia, near the plane's original flight path.
March 13 - Malaysian authorities expand their search for the missing jet into the Andaman Sea and beyond after acknowledging it could have flown for several more hours after its last contact with the ground.
Nothing was found when planes were sent to search an area off southern Vietnam identified by Chinese satellite images. The Chinese Embassy notifies the Malaysian government that the images were released by mistake and did not show any debris from the missing flight.
March 15 - Prime Minister Najib Razak's says the missing airliner was deliberately diverted and continued flying for more than six hours after losing contact with the ground. The plane could have gone as far north west as Kazakhstan or into the Indian Ocean's southern reaches.
Malaysian police have already said they are looking at the psychological state, family life and connections of pilot Zaharie Ahmad Shah, 53, and co-pilot Fariq Abdul Hamid, 27. Both have been described as respectable, community-minded men.
March 16 - The search area now includes 11 countries the plane might have flown over. The number of countries involved in the operation had increased from 14 to 25.
Malaysian defence minister Hishammuddin Hussein said he had asked governments to hand over sensitive radar and satellite data to try to help get a better idea of the plane's final movements.
March 17 - Officials release a new timeline suggesting the final voice transmission from the cockpit of the missing Malaysian plane may have occurred before any of its communications systems were disabled.
Investigators have not ruled out hijacking, sabotage, or pilot suicide, and they are checking the backgrounds of the 227 passengers and 12 crew members, as well as the ground crew, to see if links to terrorists, personal problems or psychological issues could be factors.
March 18 - Ten days after a Malaysian jetliner disappeared, Thailand's military said it saw radar blips that might have been from the missing plane but did not report it "because we did not pay attention to it".
March 19 - Distressed relatives of the missing passengers threaten to go on hunger strike over the lack of information about the investigation.
March 20 - Two objects which could be connected to the missing jet are detected in the southern India Ocean, the Australian prime minister Tony Abbott said.