Syria's military has declared the week-long ceasefire over.
In a statement on Monday, it said "armed terrorist groups" did not commit to any provisions of the brokered agreement which came into force last week.
It comes after the US-led coalition was accused of hitting a Syrian military base during an air strike killing at least 62 soldiers.
British forces were also involved in the strike, the Ministry of Defence confirmed.
Syrian military claimed armed groups had taken advantage of the truce to mobilise and arm themselves while attacking government-held areas.
The statement added the rebels had wasted a "real chance" to stop the bloodshed.
Charities such as Save the Children also accused the government of violating the ceasefire and blocking aid getting through.
The recorded death toll from the Syria conflict has now passed 300,000 since the war started in 2011.
But the Syrian Observatory for Human Rights estimates the real number is much higher at around 430,000.
Thousands of Syrians have lost their lives trying to get to Europe to escape the conflict.
The UK has pledged to resettle 20,000 Syrian refugees by 2020.