A crude oil tanker was hit by a missile off the coast of Yemen's southwestern city of Mokha overlooking the strategic Bab al-Mandeb strait, maritime security firm Ambrey said Saturday.

"A Panama-flagged crude oil tanker was reportedly 'attacked'" about 10 nautical miles southwest of Mokha, Ambrey said, adding that information "indicated the vessel was hit by a missile and that there was a fire" in the ship's rear.

The firm later said it had "received information that indicated that the tanker had received assistance. One of the steering units of the vessel was reportedly functional."

The British navy's maritime security agency said earlier it had received a report of a vessel "sustaining slight damage after being struck by an unknown object".

"The vessel and crew are safe and continuing to its next port of call," United Kingdom Maritime Trade Operations (UKMTO) added.

It said the incident occurred 98 nautical miles (180 kilometres) south of Yemen's Hodeidah, without specifying the type of vessel involved.

Iran-backed Huthi rebels who control much of Yemen have launched dozens of attacks on vessels in and around the Red Sea since November in a campaign they say is in solidarity with Palestinians in war-torn Gaza.

The attacks have prompted reprisal strikes by US and British forces and the formation of an international coalition to protect the vital shipping lanes through the Gulf of Aden and the Red Sea.