The United States military has warned of an “environmental disaster” after an attack by Yemen’s Houthi rebels on a cargo ship caused an oil slick in the Red Sea.

The Iran-aligned group hit the United Kingdom-owned, Belize-flagged bulk carrier Rubymar on February 18 with multiple missiles. It was sailing through the Bab al-Mandeb Strait which connects the Red Sea and the Gulf of Aden, on its way to Bulgaria after leaving Khor Fakkan in the United Arab Emirates.

Extensive damage prompted the crew, all of whom are safe, to abandon the ship.

US Central Command (CENTCOM) confirmed on Saturday that the ship was now “anchored but slowly taking on water”, which it said has caused a 29-kilometre (18-mile) oil slick.

The vessel was transporting more than 41,000 tonnes of fertiliser when attacked, the military said, “which could spill into the Red Sea and worsen this environmental disaster”.

“The Houthis continue to demonstrate disregard for the regional impact of their indiscriminate attacks, threatening the fishing industry, coastal communities, and imports of food supplies,” it added.

US broadcaster CNN cited an unnamed US official as saying the threat of more Houthi attacks in the Red Sea, combined with the condition of the water, makes it very difficult to safely get to the ship and attempt to tow it to a port. US officials are not sure what kind of substance is causing the slick, the report said.