Russian and US diplomats have met Lakhdar Brahimi, the international peace envoy, in Geneva for more talks on the civil war in Syria, according to Russian foreign minister.
Brahimi, joint special representative of the UN and Arab League, met Mikhail Bogdanov, Russian deputy foreign minister, and William Burns, US undersecretary of state. at an undisclosed location in the Swiss city on Sunday.
In a statement issued after lengthy closed-door talks, Brahimi said they had agreed it was still possible to find a political solution to the crisis in Syria.
"The meeting was constructive and held in a spirit of co-operation," he said.
"It explored avenues to move forward a peaceful process and mobilise greater international action in favour of a political solution to the Syrian crisis.
"All three parties reaffirmed their common assessment that the situation in Syria was bad and getting worse. They stressed that a political process to end the crisis in Syria was necessary and still possible."
They agreed that a political solution would be based on core elements of the final statement issued by major and regional powers after their last meeting in Geneva on June 30 under the chairmanship of former mediator Kofi Annan, Brahimi said.
Sunday's meeting followed Brahimi's talks this week in Dublin, Ireland, with Hillary Clinton, US secretary of state, and Sergey Lavrov, Russian foreign minister.
For his part, Lavrov said on Sunday that the US was wrong to see Russia as softening its position, but that Russia had agreed to take part in the talks on the condition there would be no demand for Syrian President Bashar al-Assad to step down.
"We are not conducting any negotiations on the fate of Assad," Lavrov said.
"All attempts to portray things differently are unscrupulous, even for diplomats of those countries which are known to try to distort the facts in their favour."
In-depth coverage of escalating violence across Syria
Lavrov said that after he agreed to a US proposal to have his and Clinton's deputies "brainstorm" on Syria, the US began to suggest that Russia was softening its position.
"No such thing," he said. "We have not changed our position."
In the wake of the Dublin meeting, Clinton said the US and Russia were committed to trying again to get both sides in the Syrian conflict to talk about a political transition.
She also said that the US would continue to insist that Assad's departure be a key part of that transition.
Russia and the US have argued bitterly over how to address the conflict, which began with peaceful protests against Assad in March 2011 and escalated into a civil war.
The US has criticised Russia for shielding its closest ally in the Middle East, while Russia has accused the US of encouraging the opposition fighters and being intent on regime change.
On the ground in Syria, activists said opposition fighters seized control of a sector of Sheikh Suleiman base, west of Aleppo, on Sunday, bringing them closer to holding a large strip of territory extending to the Turkish border in the north.
The opposition fighters took control of Regiment 111 and three other company posts located inside the base after fierce fighting overnight, the Syrian Observatory for Human Rights (SOHR) said.
Two opposition fighters and one soldier were killed, while five soldiers were captured, the UK-based watchdog group said.
"The prisoners said that 140 of their men had fled to the scientific research centre on the base," Rami Abdel Rahman, SOHR's director, told AFP news agency.
Elsewhere in northern Syria, 10 people were reported killed in government shelling of the town of Maraayan, while five civilians, including a child, were killed as Ahsam village in Idlib province was shelled, SOHR said.
Clashes were also reported around the Wadi Daif military base, which opposition fighters have been trying to take since seizing the nearby town of Maarat al-Numan two months ago.
Across the border in Lebanon, meanwhile, sectarian clashes linked to the conflict in Syria killed several people and wounded dozens more in the northern city of Tripoli, a Lebanese security official said.