A temporary truce in Syria appears to be holding as it enters its second day.
Some limited violations have taken place but no major breach. The front lines in Syria’s biggest city, Aleppo, are said to be calm.
It is the first major cessation of hostilities in Syria’s five-year war. Aid deliveries are due into besieged areas later.
Islamic State militants and the al-Qaeda linked Nusra Front are not part of the ceasefire.
More than 250,000 Syrians have been killed in Syria’s civil war and millions more have been forced from their homes.
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The “cessation of hostilities” began at midnight on Saturday (22:00 GMT Friday) with battlezones largely quiet.
However, Syrian state media said several shells had hit residential areas of the capital, Damascus, on Saturday. It did not say who had fired.
Low-level clashes have also been reported between rebel groups and government forces elsewhere.
The Russian Foreign Minister, Sergei Lavrov and the US Secretary of State John Kerry have spoken by phone, welcoming the ceasefire and, Moscow says, discussing ways of supporting it through military co-operation.
The truce involves Syrian government and rebel forces, but not the so-called Islamic State group (IS) or the al-Qaeda-linked Nusra Front.
The US confirmed it had continued to attack IS targets in Syria on Saturday, including near Tal Abyad close to the Turkish border.
UN special envoy for Syria Staffan de Mistura has said that peace talks will resume on 7 March if the truce “largely holds”, adding that he had no doubt there would be “no shortage of attempts to undermine this process”.
The cessation was brokered by the US and Russia, and is backed by a UN resolution. Previous talks in Geneva collapsed in early February after making no progress.
One of the key aims of the cessation is to allow desperately needed aid to reach people trapped in besieged areas.
The UN resolution names about 30 areas in dire need of aid, including eastern and western rural Aleppo and the eastern city of Deir al-Zour, which is under siege by IS.
Almost 100 rebel factions have agreed to respect the truce, the Syrian opposition umbrella group the High Negotiations Committee (HNC) says.
However, the HNC warned the Syrian government and its allies not to use the “proposed text to continue the hostile operations against the opposition factions under the excuse of fighting terrorism”.
Russian President Vladimir Putin says his forces are targeting IS, Nusra Front and other extremist groups designated as legitimate targets by the UN Security Council.
However, over the course of its campaign in Syria, Russia has been widely accused of also attacking more moderate rebel groups fighting President Assad, an ally of the Kremlin.
Syria’s civil war
Why is there a war in Syria?
Anti-government protests developed into a civil war that four years on has ground to a stalemate, with the Assad government, Islamic State, an array of Syrian rebels and Kurdish fighters all holding territory.
What’s the human cost?
More than 250,000 Syrians have been killed and a million injured. Some 11 million others have been forced from their homes, of whom four million have fled abroad – including growing numbers who are making the dangerous journey to Europe.
How has the world reacted?
Iran, Russia and Lebanon’s Hezbollah movement are propping up the Alawite-led Assad government, while Turkey, Saudi Arabia and Qatar back the more moderate Sunni-dominated opposition, along with the US, UK and France. Hezbollah and Iran have pro-Assad forces on the ground, while a Western-led coalition and Russia are carrying out air strikes.