The FSO Safer supertanker — moored off the Yemeni coast and containing over a million barrels of oil — will “sink or explode at any moment,” wreaking devastation, the UN has warned.

“We don’t want the Red Sea to become the Black Sea. That’s what’s going to happen. It’s an ancient vessel from 1976 that’s unmaintained and likely to sink or explode at any moment,” David Gressly, UN humanitarian coordinator for Yemen, told Sky News.

“Those who know the vessel, including the captain who used to command the vessel, tell me that it’s a certainty. It’s not a question of ‘if,’ it’s only a question of ‘when’.”

Given the million-plus barrels of oil on the Safer, Gressly said it is vital that action is taken quickly, with scientific modeling suggesting that an oil spill would hit Yemen’s Red Sea ports of Hodeidah and Salif “within days,” abruptly ending food aid relied on by 6 million people.

Furthermore, it would lead to a cessation of “most” fuel imports essential for the functioning of pumps and trucks supplying fresh water to some 8 million people.

While the catastrophe can be impeded at a cost of $130 million — a figure dwarfed by the potential $20 billion clean-up cost — the UN finds itself some $34 million short, and has even resorted to using crowdfunding to purchase a rescue tanker for the hoped-for salvage operation.

“There are complexities, but for most member states the difficulty — and it’s ironic — is there’s plenty of money available in state budgets for a response to an emergency, but nobody seems to have budget lines for avoiding a catastrophe,” said Gressly.

Nor is Yemen the only country at risk, with the modeling suggesting that the oil spill would hit the coasts of Saudi Arabia, Eritrea and Djibouti within two to three weeks, leading to profound environmental impacts for coral reefs and protected coastal mangrove forests.

With the entirety of Yemen’s Red Sea fishing stock facing extinction, the concern is the upending impact on the millions of people reliant on the ocean for their food and livelihoods.

Hisham Nagi, professor of environmental science at Yemen’s Sana’a University, told Sky News: “The oil tanker is unfortunately located near a very, very healthy coral reef and clean habitat, and it has a lot of species of marine organisms.

“Biodiversity is high in that area, so if the oil spill finds its way to the water column, so many marine sensitive habitats are going to be damaged severely because of that.”