Yemen's Shia rebels say they have endorsed a U.S.-brokered cease-fire deal, confirming an earlier announcement by U.S. Secretary of State John Kerry on their conditional acceptance of the proposal.

A spokesman for the rebels known as Houthis told the rebel-run Al-Masirah TV late on Wednesday that they agree to a cease-fire, the forming of a national unity government and discussing ways to end the conflict.

However, Yemen's internationally-recognized government has dismissed the deal as "unilateral." Kerry had said the cease-fire was to start on Thursday.

Yemen's conflict pits pro-government forces and a Saudi-led coalition against the rebels and their allies. Several attempts to negotiate an end to the war have failed.

Fighting escalated on Thursday in the western city of Taiz, where government forces expelled the Houthis from several districts.