A cargo ship master has reported being followed for an hour by 12 smaller boats in the southern Red Sea.
UK Maritime Trade Operations said the incident took place in the early hours of Sunday, 13 nautical miles (24 km) south-west of Mokha in Yemen.
The vessel was not named but its captain said the swarm of smaller craft included fast vessels and smaller kayak-type boats, some of which appeared to be uncrewed.
The closest point of approach was 1.5 nautical miles.
The boats remained near the vessel for an hour before leaving the area, UKMTO said.
The ship and its crew were reported safe, and the vessel proceeded to its next port of call.
Authorities are investigating, UKMTO added.
Security company Africa Risk Compliance (ARC) classed the incident as a “suspicious approach”.
In recent weeks, the Houthi militia has been intensifying its attacks against vessels they view as taking part in trade with Israel.
On Friday, there were fears of a fresh attack in the southern Red Sea.
UKMTO reported an incident had been reported 150 nautical miles north-west of the Yemeni port of Hodeidah.
Greek bulker targeted?
ARC said the master reported five missiles landing close to a vessel.
The ship was not damaged and proceeded north through the Red Sea.
The location was north of Thursday’s attack on an unspecified cargo ship, in which Yemen’s Houthi militia deployed sea drones and other projectiles to target a vessel it said had “violated a ban on visits to ports in occupied Palestine [Israel]”.
It named that ship as the Seajoy, saying it had been targeted by “a UAV [unmanned aerial vehicle], missile and naval forces using an uncrewed surface boat”.
Greek owner Eastern Mediterranean Maritime owns a Malta-flagged, 73,500-dwt 2000-built bulker of that name.
The company has not responded to a request for comment.
Houthi military spokesman Yahya Saree said the attack scored a “direct and accurate hit”.
Diaplous Group said the alert from the vessel believed to be the Seajoy was transmitted through VHF channel 16 in the southern Red Sea, about 84 nautical miles south-west of Hodeidah in Yemen.
Sea drones were used to sink a Greek bulker in June. A video distributed on media channels and social media purported to show a sea drone approaching Evalend Shipping’s 82,000-dwt Tutor (built 2022).
