Somali pirates are suspected of hijacking a bulk carrier ship on one of the world's crucial trade routes, Reuters reported.
The United Kingdom Maritime Trade Operations piracy watchdog said on its website it had received a report from a vessel under attack and possibly boarded off the coast of war-ravaged Yemen. It gave no further details.
However, a security source working at the Puntland Marine Police Force said the vessel was Tuvalu-flagged and is known as OS35. Graeme Gibbon-Brooks, the head of private company Dryad Maritime Intelligence, said industry sources had confirmed the hijacking.
"Vessels transiting the area are advised to exercise extreme caution," UKMTO said, without giving more details.
The hijacking comes days after pirates hijacked an Indian dhow that was on route to Bossaso from Dubai.
Somali pirates in recent weeks have hijacked at least two vessels with foreign crews in the waters off Somalia and Yemen, marking a return of the threat after half a decade.