Syrian planes attack Islamic State positions in Palmyra
Syrian planes are pounding the Islamic State-held town of Palmyra, killing at least 15 people in a series of air strikes, according to activists.
They say the attacks are some of the heaviest since the extremist group seized the ancient town in central Syria on May 10. A local activist reported around 30 air strikes.
The strikes come a day after the Syrian army carried out heavy air raids in the northern city of Raqqa, also held by Islamic State.
The Syrian government says it is the leading force fighting IS in Syria. Russia, a key ally of president Bashar Assad, is trying to convince the West of the need to work with Syria in the fight against IS.
Moscow said it would consider sending troops to fight in Syria if Damascus asked for them, a spokesman for president Vladimir Putin said.
Dmitry Peskov spoke in response to comments by Syrian foreign minister Walid al-Moallem, who denied reports that Russian combat troops were fighting with Syrian forces, but said Syria would ask for Russia's help if needed.
If such a request is made, it will be "discussed and considered", Mr Peskov said.
US secretary of state John Kerry said Washington is planning direct talks with Russian military officials over Moscow's growing involvement in Syria.
He said president Barack Obama believes such discussions are an important next step as the US and its allies seek to resolve a worsening crisis.
The Pentagon will take the lead in the discussions but the exact level, venue and timing have yet to be determined.
Most military talks with Moscow were suspended after Russia annexed the Crimea region of Ukraine.
The Britain-based Syrian Observatory for Human Rights said a number of IS militants were among those killed in Palmyra.
Meanwhile, a coalition of rebel groups launched a major ground offensive on two predominantly Shiite villages in the northern province of Idlib, firing dozens of rockets and detonating at least seven booby-trapped vehicles on the outskirts.
The coalition, known as Jaysh al-Fateh, or "Army of Conquest", attacked Foua and Kfarya villages. Both are held by pro-government forces in an otherwise rebel-controlled province.
Syrian TV and Manar, a station owned by Lebanon's Hezbollah group, said popular defence forces - a term used to refer to Shiite militias - foiled attempts by "terrorists" to attack Foua and destroyed five armoured vehicles. Hezbollah fighters are also battling to defend the two villages.
Syrian government forces have pulled out from Idlib province over the past year following major gains by the rebel coalition. The two villages are the only remaining pro-government posts in the region.
The Army of Conquest alliance, which includes Syria's al Qaida branch the Nusra Front and the extremist Jund al-Aqsa group, is backed by Turkey and Saudi Arabia.
More than 250,000 people have died in Syria's civil war, according to UN officials.