ADEN, Yemen, May 2 (Xinhua) -- A second incident involving a commercial vessel being approached by unidentified boats has been reported in waters south of Yemen, a British maritime security agency said Saturday.

The United Kingdom Maritime Trade Operations (UKMTO) said in a statement posted on social media platform X that it had received a report of a "suspicious approach" approximately 84 nautical miles southwest of Al Mukalla.

According to the agency, the master of a bulk carrier reported that a green-hulled skiff, accompanied by a white fishing vessel, approached to within 500 meters of the ship.

The development comes less than 24 hours after the UKMTO issued a separate warning about another encounter in nearby waters.

In that earlier case, the master of a bulk carrier reported being approached by a skiff with a black hull carrying seven armed individuals.

No injuries or damage have been reported in either incident.

Amid the ongoing tensions in the Middle East, Iran and Yemen's Houthis have repeatedly warned of a possible return to attacks on commercial shipping in the Red Sea and the Bab al-Mandab Strait.

The threats have heightened concerns about the safety of one of the world's most vital maritime routes. However, despite the repeated statements, there have been no clear indications so far of a renewed campaign targeting vessels in the area. ■