Yemen's exiled government said it would not attend planned UN-brokered peace talks unless Shiite rebels first agree to withdraw from territory they have captured in accordance with a UN resolution.
A short statement published by the exiled president's office overnight said the government had decided "not to take part in any meeting until the militia recognises Resolution 2216 and agrees to implement it without conditions".
The statement appeared to go back on a previous statement last week in which the exiled government said it would attend the planned talks in neutral Oman.
The UN's special envoy for Yemen, Ismail Ould Cheikh Ahmed, had announced that both the government and the rebels had agreed to take part.
The talks were aimed "at creating a framework for an agreement" on a UN mechanism that would see the Huthis withdraw from territories that they have conquered, the envoy said.
The United Nations has called repeatedly for a ceasefire in Yemen, but talks in Geneva in June collapsed without the warring parties even sitting down in the same room.
Impoverished Yemen has been wracked by conflict since March, when a Saudi-led Arab coalition launched air strikes against the Iran-backed Huthis.
Oman is the only Gulf Arab state that has not joined the coalition.