Britain and Russia are to restart talks on resolving the crisis in Syria, following discussions between David Cameron and Vladimir Putin last night.

The two leaders, who have halted almost all international co-operation since Russia invaded Ukraine last year, agreed to restart the dialogue on dealing with the rise of Islamic State (ISIS), which poses a threat to both countries.

They spoke for 30 minutes after the Russian President telephoned Mr Cameron to congratulate him on his 'major success' in the election.

Britain and Russia are to restart talks on resolving the crisis in Syria, following discussions between David Cameron and Vladimir Putin last night. Pictured: The two leaders at the G20 summit in Brisbane in November

The two men agreed that the Prime Minister's national security adviser Sir Kim Darroch will hold talks with his Russian counterpart in the coming weeks to try to find a solution to the bloody civil war in Syria.

'Both leaders agreed that it is in the interest of both the UK and Russia to help find a solution to the civil war in Syria and particularly to stop the rise of ISIL,' a spokeswoman said.

'They agreed that their national security advisers should meet to restart talks on the Syrian conflict. The Prime Minister reiterated his belief that President Assad could not be part of the solution in Syria.

'And they agreed that both countries should continue talks with the moderate Syrian opposition as part of this effort.'

Relations on Syria have been at rock bottom since the civil war started in 2011.

Syrian tyrant Bashar al-Assad counts Moscow as his staunchest ally.

In 2013 Mr Cameron accused Mr Putin of having the blood of Syrian children on his hands by backing the dictator who has massacred his own people.

The pair agreed to restart the dialogue on dealing with the rise of Islamic State (ISIS), which poses a threat to both countries (file picture)

But the rise of ISIS has raised the prospect of possible co-operation.

Downing Street said the prime minister warned Mr Putin that any deal must include the removal of President Assad. Sources said the two men agreed to 'continue talks with the moderate Syrian opposition'.

Mr Cameron also criticised Russia's continued occupation of the Crimea and its aggression in Ukraine.

Downing Street said there remained 'deep differences' over Russia's role in the instability of its neighbour 'but that the priority now must be to deliver full implementation of the Minsk agreement.