Maritime security firm Ambrey on Wednesday reported an "explosion" near a Barbados-flagged, US-owned bulk carrier southwest of the Yemeni port city of Aden.
"A nearby vessel reported an explosion in the proximity of the Barbados-flagged, publicly US-owned bulk carrier," Ambrey said.
It cautioned other ships to steer clear of the ship, which it said matches the "targeting profile" of Yemen's Iran-backed Huthi rebels.
British maritime security agency UKMTO said the ship "is reported to have been hit and has suffered damage".
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.
Before the latest reported attack, Ambrey said the bulk carrier was "hailed by an entity declaring itself to be the 'Yemeni Navy'," a title adopted by the Huthi rebels.
The attacks 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.
