The United Nations has released stark satellite images showing recent destruction in Syria's embattled northern city of Aleppo following air strikes.
The city has been pounded by Syrian and Russian planes since the collapse of a US-Russia brokered ceasefire two weeks ago.
The release coincides with a stepped-up offensive by Syrian pro-government forces which are attacking the city from the south in a bid to penetrate its opposition-controlled areas, where the UN estimates 275,000 people are trapped in a government siege.
In Geneva, an official with the UN's satellite imagery programme, Unosat, said the new pictures from the rebel-held areas in the eastern half of the city show much destruction, presumably caused by air strikes.
Researcher Lars Bromley said: "Since the ceasefire has broken down, you certainly see an awful lot of new damage or plenty of new damage."
He said the images, from Digital Globe and obtained by the UN agency through a licensing arrangement with the US State Department, show mostly "formerly blasted and blown-up areas" during Syria's five-and-a-half year war "experiencing a great deal of additional damage."
"To a certain extent you're looking at rubble being pushed around," he told reporters.
The images primarily show before-and-after pictures from mid to late September showing the destruction of buildings, including houses, after the short-lived ceasefire broke down.
Several images are from northern Aleppo areas, where government forces have also advanced against rebel fighters battling back.
Mr Bromley added: "Since the ceasefire has broken down, you certainly see an awful lot of new damage or plenty of new damage.
"Remember that the areas that are being bombed have been bombed almost continuously for quite some time. So seeing dramatic images of formerly pristine areas now turned to rubble - you don't see a lot of that."
One image, dated from Saturday, shows the damage to a school or athletic facility in Aleppo's Owaija district.
Some of the images bore a "signature" which showed air strikes had caused the damage: a large-sized crater.
"Air-dropped munitions are often much larger than anything you would fire on the ground, so a giant crater in the ground is almost certainly an air-dropped munition," Mr Bromley explained.
"Then things like rockets, they will often occur in a row, whereas artillery or mortars will kind of have a different pattern.
"But there is also a lot of overlap, there is a lot of smaller air-dropped bombs that will look almost the same as a mortar or an artillery piece."
Unosat manager Einar Bjorgo added that places like Aleppo, which has long been the focus of Syria's bitter civil war "are of course complex to analyse because you have a mix of all this".
The images could also provide significant insight after a controversial attack - such as a deadly attack on a UN-backed humanitarian aid convoy west of Aleppo last month.
"With our analysis, we determined that it was an air strike," Mr Bromley said. Convoy organisers had obtained necessary clearances from the government, rebels as well as the Americans and Russians, who operated aircraft in Syrian skies.
The top US military officer, Marine Gen Joseph Dunford, chairman of the Joint Chiefs of Staff, told a Senate committee last week that he believes Russia bombed the convoy and said Syrian and Russian aircraft were in the area at the time. Russia and Syria have denied that they were responsible for the strike.
Meanwhile, overnight air strikes, suspected to have involved Turkish planes, have hit a village in northern Syria, killing at least 18 civilians.
The UK-based Syrian Observatory for Human Rights says that at least 19 were killed, including three children, in the attack on the majority Kurdish village of Thulthana, in northern Aleppo province.
The village is in an area controlled by Islamic State militants.
The Hawar news agency in the semi-autonomous Kurdish areas in Syria said 18 were killed.
There was no immediate comment from Ankara.
Turkish military launched an offensive inside Syria in August, backing Syrian rebels, to push IS fighters from its borders and curb advances of Syrian Kurdish rebels, which it sees as an extension of its own outlawed Kurdish rebels.