The U.K. government says it has contributed £2.5m ($3.3m) to fund an international mission to assess the state of a stricken tanker in Yemeni waters which holds an estimated 1.14 million barrels of crude oil.

That is about a third of the $9m cost of an initial assessment mission for the SFO Safer, according to estimates by the United Nations.

The figures were revealed by the U.K.’s Foreign, Commonwealth & Development Office (F.C.D.O.) in response to a Freedom of Information request.

However, most of the U.K.’s pledge has yet to be spent. To date, London has spent £156,000 on research to identify and assess the threat posed by the tanker.

The UN wants to send a team to visit the tanker to check its condition, conduct urgent repairs and assess how best to extract the oil on board safely. However, it has been hampered by the continued failure of the Houthi rebels – who control the area where the tanker is moored – to allow an international team to visit the tanker.

“The UN is unable to properly assess the vessel and recommend further action until the Houthis have allowed the experts to access the vessel,” the F.C.D.O. said.

It is not clear if the remaining funding that is needed has already been pledged by other countries, although the U.K. says it has lobbied its partners “to ensure adequate funding is in place.”

In July, U.N. humanitarian affairs chief Mark Lowcock said financing for an initial mission had yet to be found. “We understand that [U.N.] member states are working to finalize funding to pay for the UN mission,” he told the Security Council on July 15.

Risk of environmental disaster

The U.K. says it is also working with the U.N. and countries with Red Sea coastlines to develop “robust contingency plans” in case oil starts leaking from the vessel.

The FSO Safer’s cargo is four times larger than the oil aboard the Exxon Valdez when it ran aground in Alaska in 1989. The U.K. minister for the Middle East, James Cleverly, said in a statement in July that the situation today in Yemen was “an environmental disaster waiting to happen.”

A joint communiqué issued by Germany, Kuwait, Sweden, the U.K., the U.S., China, France, Russia and the European Union on September 17 called on the Houthis to “urgently facilitate unconditional and safe access for U.N. experts to conduct an assessment and repair mission.”

Countries in the region are also increasingly concerned. An emergency meeting of Arab environmental affairs ministers was hosted by Saudi Arabia on September 21 at which they called for more pressure to be brought on the Houthis to allow access to the tanker.

As yet, however, there has been no sign of access being granted.