A truce in place since last Thursday in the Syrian city of Aleppo has been extended for two days until midnight on Wednesday, Syrian state TV says.
The truce had been due to run out at 01:00 local time on Tuesday. It has already been extended once.
Deadly clashes in the two weeks leading to the truce had killed 300 people.
The US and Russia see Aleppo as key to bolstering a nationwide truce they brokered between the army and non-jihadist rebels in February.
That cessation of hostilities had come under increasing pressure with numerous violations, not least in Aleppo.
The agreement is only partial, as it does not include the al-Qaeda-linked Nusra Front nor so-called Islamic State.
A screen caption on Syrian state TV about two hours before the truce was due to expire read: "The General Command of the Armed Forces: The system of calm in Aleppo and its countryside extended for 48 hours starting from 01:00 on Tuesday [2300 GMT on Monday] until 24:00 on Wednesday [22:00 GMT]."
The US had earlier said that it wanted an end to piecemeal ceasefires and a return to a working nationwide cessation of hostilities so faltering peace talks could be resumed.
Talks in Geneva last month broke up amid acrimony.
The US and Russia back opposite sides in the conflict, with Moscow the ally of President Bashar al-Assad.
US Secretary of State John Kerry said the US and Russia should both press the parties they support to observe a meaningful nationwide truce.
Despite the Aleppo agreement there has been fighting between the military and rebel groups outside the city.
The UK-based Syrian Observatory for Human Rights monitoring group said government war planes had struck the town of Khan Touman, south-west of Aleppo, on Monday.
Aleppo, in north-west Syria, was the country's industrial and financial centre before the five-year civil war started.