A top Russian diplomat says a threat from the United States to halt cooperation with Russia in the Syria conflict constitutes an "emotional breakdown" and says Russia is willing to support a 48-hour cease-fire around Aleppo.
Deputy Foreign Minister Sergei Ryabkov rejected Washington's calls for a seven-day pause in hostilities, but said Russia is willing to support a 48-hour truce for humanitarian purposes.
Mr Ryabkov's comments follow US Secretary of State John Kerry's warning that the US will stop coordinating with Moscow unless Russian and Syrian attacks on Aleppo end.
Mr Ryabkov was quoted by Russian news agencies as saying of the US that "a certain emotional breakdown occurred".
He also reiterated Russia's stance that a seven-day pause in the Aleppo offensive would give militant groups time to regroup.
Syria's military has released a video of its new advances in the contested city of Aleppo, showing destruction and ruins in a neighbourhood that is hundreds of years old.
The video released on Thursday shows damaged traditional buildings, with arched ceilings and stone walls, in the Farafra neighbourhood that rests at the foot of the old citadel in Aleppo city.
The video shows mounds of debris, twisted metal bars and broken ceilings with fighters walking past.
Syria's government claimed it had repelled rebels from Farafra on Tuesday, in the first such advance in old Aleppo.
Since last week, the government has waged a major air campaign in Aleppo and threatened a wide ground offensive. The charity Doctors Without Borders says more than 270 civilians have been killed in the advance.
Meanwhile, Turkish President Recep Tayyip Erdogan says his country is determined to eliminate the "corridor of terror" along its border with Syria by clearing the Islamic State group and Syrian Kurdish fighters from the area.
Addressing a group of local administrators, President Erdogan reiterated that a secure no-fly zone which Turkey would like established in Syria would help end the flow of refugees to Turkey and beyond.
Turkey last month sent troops and tanks into Syria to help Syrian opposition rebels re-take IS strongholds near the Turkish border and curb the advance of Syrian Kurdish militia, which are affiliated with Turkey's outlawed Kurdish rebels.
President Erdogan said some 30,000 people had returned to the Syrian town of Jarablus since it was freed from IS by the Turkish-backed rebels last month.