MANAMA: The US navy said Sunday it had stopped a ship carrying 40 tons of a fertiliser that can be used to make explosives as it travelled from Iran along a route previously used to smuggle weapons to Yemen's Huthi rebels.

The navy said it boarded and searched the ship, which last year was caught carrying thousands of weapons and handed to Yemen's coast guard, after intercepting it in international waters in the Gulf of Oman on Tuesday.

A US guided-missile destroyer and patrol ship "interdicted the stateless vessel transiting from Iran... along a route historically used to traffic weapons to the Huthis in Yemen," the Bahrain-based US 5th Fleet said.

"US forces discovered 40 tons (36,300 kilos) of urea fertiliser, a chemical compound with agricultural applications that is also known to be used as an explosive precursor," it added.