A Barbados-flagged, US-owned bulk carrier was struck Wednesday southwest of the Yemeni port city of Aden, triggering a naval operation to rescue the crew, a maritime security firm said.

"Reports confirmed the bulker had been struck and sustained damage," Ambrey said, adding that a rescue operation was "underway with parts of the crew already in lifeboats".

It did not elaborate on the attack but cautioned other ships to steer clear of the bulker, which it said matches the "targeting profile" of Yemen's Iran-backed Huthi rebels.

The Huthis started harassing ships in the Gulf of Aden and the Red Sea in November, a campaign they say is intended to signal solidarity with Palestinians amid the Gaza war.

They have vowed to strike Israeli, British and American ships as well as vessels heading to Israeli ports, disrupting traffic through the vital trade route off Yemen's shores.

The United Kingdom Maritime Trade Operations, a British maritime security agency, said vessels in the vicinity of the bulker had reported "a loud bang, and a large plume of smoke".

It said the ship "is reported to have been hit and has suffered damage".

Ambrey earlier said the bulk carrier was "hailed by an entity declaring itself to be the 'Yemeni Navy'," a title adopted by the Huthi rebels.

The flurry of strikes have caused several major shipping firms to suspend passage through the Red Sea, which usually carries around 12 percent of global trade.

At least "15 commercial ships have been impacted" since November, including four US ships, US department of defence spokesman Pete Nguyen said on Friday.

The United States and Britain have since January launched repeated strikes on Huthi targets in Yemen in response to the ship attacks.