Russia has bombed 70 Islamic State targets in Syria, in the heaviest strikes there since the war began.

Strongholds in cities and towns were hit, as well as three oilfields controlled by the militant group.

The strikes came as the UN Security Council passed a motion calling for action against IS.

Britain's ambassador to the UN Matthew Rycroft says it's a significant step.

"The whole international community has come together all 15 members of the Security Council who come at this issue at very different starting points, so I think that it is significant that all of them have come together to support this powerful resolution."