The United Nations Security Council called on Houthi rebels to allow inspectors to visit a long-abandoned fuel tanker off Yemen "without further delay" on Thursday.

The 15-member council held a special meeting on FSO Safer at the request of Britain after the rebels said an agreement to allow the UN mission had "reached a dead end".

The 45-year-old fuel vessel FSO Safer has 1.1 million barrels of crude on board and has been abandoned near Yemen's western port of Hodeida since 2015.

The UN says it threatens a catastrophic oil spill that would destroy Red Sea ecosystems, shut down the fishing industry and close Yemen's lifeline Hodeida Port for six months.

Members urged the Houthis to "facilitate unconditional and safe access for UN experts to conduct a comprehensive and impartial assessment and initial repair mission without further delay", a statement said.

UN inspectors were initially meant to assess the tanker last year but the mission has been repeatedly delayed over disagreements with the rebels.

The Houthis insist that the UN team conducts maintenance work but the world body says it must be allowed to assess the site first before carrying out any works.

On Tuesday, the Houthi rebels said negotiations with the UN had reached an impasse after several days of talks.

The UN's Office for the Coordination of Humanitarian Affairs told the council meeting that the UN team "remains ready to deploy".

"The UN will keep that team on stand-by for as long as we have donor funding to do so," said OCHA's director of operations and advocacy, Reena Ghelani.

"Some of those funds, however, will start running out soon, so we hope things will start moving much, much faster," she said.