LONDON: US Secretary of State John Kerry said his Russian counterpart Sergei Lavrov had agreed on the need to discuss how to implement a ceasefire in Syria during a call between the two men on Thursday.

Speaking at the start of a Syrian donor conference in London, Kerry said he had spoken to the Russian foreign minister who also agreed on the need to find a way to get humanitarian access for both parties.

"I had a conversation this morning with Foreign Minister Lavrov. We discussed, and he agreed that we need to discuss, how to implement the ceasefire and also how to get (humanitarian) access by both parties," Kerry told reporters.

Kerry also said Russia had a responsibility to live up to the United Nations commitment to provide humanitarian access and cease attacks on Syrian civilians.