Britain wants Syrian President Bashar al-Assad to leave power 'at some point' as part of any deal by world powers to end the conflict, Foreign Secretary Philip Hammond said on Tuesday.

"We are ready to engage with anyone who is willing to talk about what that political transition in Syria might look like, but we are very clear from our point of view it must involve, at some point, the departure of Bashar al-Assad," Hammond told lawmakers in the House of Commons.