UN envoy Staffan de Mistura said Tuesday a faltering truce in Syria must be "brought back on track" as he held talks in Moscow with Russian Foreign Minister Sergei Lavrov on ending a fresh upsurge in fighting, AFP reports.

As the talks kicked off in Moscow, fighting raged in Syria's second city of Aleppo, with state media reporting that rebel fire on a hospital killed three
women. Another 11 people were killed in rebel attacks on other government-held neighborhoods, SANA state news agency said.

In televised remarks, de Mistura praised the two-month-old truce brokered by Moscow and Washington as a "remarkable achievement" and said the two global powers should help "all of us to make sure that this is brought back on track".