Two drones followed a merchant vessel in the Red Sea, west of Saudi Arabia's Jizan, in a suspicious approach, but the ship continued its journey safely, the United Kingdom Maritime Trade Operations (UKMTO) agency said on Monday.
The two Uncrewed Aerial Systems (UAS) followed the vessel for about 30 minutes, UKMTO said in an advisory note.
"The UAS were assessed to be at a height of 100 m above the vessel and are now reported to have cleared the area. Vessel and crew are safe," the note said.
The Iran-aligned Yemeni Houthis have carried out repeated drone and missile strikes since November in the Red Sea and Bab al-Mandab Strait, saying they are acting in solidarity with Palestinians in the Gaza war.
U.S. and British forces have responded with multiple strikes on Houthi facilities but have so far failed to halt the attacks.
Reporting by Hatem Maher and Adam Makary