A deal for Yemen's veteran leader to hand over power and end unrest looks in doubt after President Ali Abdullah Saleh failed to sign it.

He had been expected to add his signature on April 30 after his officials said the deal brokered by Gulf Arab states had been accepted.

Mr Saleh reportedly said he would only sign the agreement in his capacity as head of the ruling party.

Opposition spokesmen insist he must sign as president.

The Gulf states' mediator, Abdul-Latif al-Zayyani, is now believed to have left the capital, Sanaa, BBC reported.