The SAFER FSO, owned by Yemen’s leading oil company FSO, is a large oil tanker that has been permanently moored 7km off the Red Sea port of Ras Isa since 1988.

A Floating Storage and Offloading (FSO) terminal, it has acted as an offshore platform for vessels loading crude oil from the Marib-Ras Isa pipeline, to which it was connected.

In early 2015, Houthi forces captured the port and, in the two years that followed, oil operations were scaled back prior to the port’s closure, which was forced by the Saudi-led coalition’s naval blockade and a series of airstrikes on its infrastructure.

During that time, the SAFER FSO, which is still thought to contain 1.14 million barrels of crude oil, fell into disrepair.

Now there are fears that gases have built up in the storage tanks, which means the ship could explode.

Additionally, having a single hull, experts say the ship is at particular risk from corrosion.

Despite these, UN officials’ plans to visit the ship and assess the scale of the damage have been blocked, the UN humanitarian coordinator Mark Lowcock told the UN security council last week.

The UN assessment team had planned to deploy to the tanker next week, but the necessary permits remain pending with the Ansar Allah authorities. Discussions continue to resolve this as quickly as possible. And I would just like to note that this is additionally frustrating when one recalls that the same authorities wrote to the United Nations early last year requesting assistance with the tanker and promising to facilitate our work,

...he said.

The two sides in the conflict in conversation with the UN blame each other for failing to reach a solution about what to do about the ship.

The Houthis want guarantees that they will be able to control the revenues from the oil on the ship valued at $80m (£64m), a move that might require a new oil export mechanism, according to The Guardian.

The Yemen government points out that the oil onboard is four times the amount of oil released in the 1989 Exxon Valdez oil spill, one of the worst environmental disasters in shipping history.