Russian President Vladimir Putin has said that he discussed with visiting British Prime Minister David Cameron possible joint measures to end the conflict in Syria.
Putin's comments on Friday came as Sergei Lavrov, the Russian foreign minister, said that the long-term ally of Syrian President Bashar al-Assad was completing its delivery of surface-to-air missiles to Syria.
"Russia is not planning to sell, Russia has sold a long time ago, and is completing supplies of the equipment - which is anti-aircraft systems, according to the already signed contracts," Lavrov said in Warsaw.
Lavrov said earlier that Moscow did not plan to sell its advanced S-300 air defence system to Syria, but left open the possibility that it could ship such systems to Damascus under an existing contract.
Putin said he had discussed possible options for a positive development of the situation in Syria with Cameron.
"We have a joint interest in a swift halt to the violence and the creation of the process for a peaceful solution that keeps Syria's territorial integrity and sovereignty," Putin said.
Assad sticking point
The West and Russia have been repeatedly at odds over the Syria conflict, with the United States and Europe accusing Moscow of seeking to prop up Assad and supplying Damascus with military hardware.
In-depth coverage of escalating violence across Syria
Cameron said it was no secret that Russia and Britain had different positions on the Syria conflict but they shared an ultimate aim of halting the bloodshed, allowing the Syrian people to elect a government and preventing a growth in extremism.
The British leader said he fully backed the outcome of a meeting between the top US and Russian diplomats this week who agreed to make a joint effort in search of a solution.
However, Assad remains a sticking point to any deal.
Al Jazeera's Hashem Ahelbarra, reporting from Istanbul in Turkey, said the rebels would reject any deal that involved Assad and it remained to be seen whether the British and the Americans could convince the Russians that Assad's days were over.
The crucial talks on reaching a peace deal came as Syria's army said it had dropped leaflets over a province in Homs that told people to leave ahead of an attack.
However, an activist Al Jazeera spoke to in the town of Qusayr, near Lebanon, said no leaflets had been dropped.
Ahelbarra said a senior rebel commander had told him that the Syrian army had recaptured most of the villages around Qusayr and that the town itself was under intense shelling from security forces.
"He also says that Hezbollah is using long-range artillery to pound rebels' hideouts," Ahelbarra said.
"This comes against a backdrop of a new context, where the Syrian army appears to be reversing the tide of the advancement of the rebels, making some significant gains towards areas controlled by the rebels.
"This is exactly why the international community and particularly the United Nations High Commissioner for Human Rights is concerned about what might happen in those areas if they come under the control of the Syrian army and they are also concerned about any potential or future crimes against civilians".
Navi Pillay, the UN's human rights commissioner, said on Friday that those responsible for rights abuses in Syria must be held accountable for their crimes.
She also expressed concern over reports of a major military build-up around Qusayr and said that she feared further atrocities if the area was overrun.