This follows reports that more than 50 displaced people were killed in an air strike in north-west Tigray on Friday.

A White House statement said the US president welcomed the release of opposition leaders and pledged support in finding a peaceful end to the war with Tigrayan rebels.

Relations have not been good between Washington and Addis Ababa where the government has been upset by repeated criticism of human rights abuses during the war with Tigrayan rebels.

The fact that Mr Biden and Mr Abiy held a phone conversation at all is perhaps a sign of progress.

The White House statement says the two leaders discussed ways to accelerate dialogue towards a negotiated ceasefire.

It also says the recent release of opposition leaders was a positive step. But the subject of atrocities was once again raised.