The Iran-aligned Houthi movement that controls northern Yemen hijacked a United Arab Emirates-flagged cargo vessel which it said was engaged in "hostile acts" but which the Saudis said was carrying hospital equipment.
The ship was heading to the Saudi port of Jizan, just north of Yemen, from the Yemeni Red Sea island of Socotra when it was attacked just before midnight on Sunday, Saudi state news agency SPA reported, quoting coalition spokesman Brigadier General Turki al-Malki.
Saudi Arabia is leading a military coalition that has been battling the Houthis for more than six years. The alliance has accused the Houthis of attacking shipping in the Red Sea, one of the world's busiest maritime lanes leading to the Suez Canal.
The cargo ship was hijacked off the western Yemeni port of Hodeidah, the coalition said.
The Houthis' military spokesman, Yahya Sarea, confirmed the seizure of the vessel which he said was carrying military equipment and engaged in "hostile acts targeting the security and stability of the Yemeni people." He added that the crew, "of different nationalities," was still on board.
In a press briefing broadcast on the group's Masirah TV, Sarea shared photos and videos that he said they were of the seized ship showing armored vehicles, weapons and ammunition. He added the vessel had been taken to the Houthi-controlled port of Salif, north of Hodeidah.
SPA said the vessel was carrying equipment from a shuttered field hospital.
The United Kingdom Maritime Trade Operations (UKMTO) said late on Sunday it had received reports of an attack on a vessel near Yemen's port of Ras Isa, which lies slightly north of Hodeidah, and an investigation was underway.
In an advisory issued at 2150 GMT, 0050 local time, UKMTO - part of Britain's Royal Navy - advised mariners to exercise extreme caution in the area.
It put the vessel's position at approximately 23 nautical miles west of Ras Isa oil terminal in the Red Sea.
The last attack near Ras Isa was in late 2019 when the Houthis briefly seized a Saudi-flagged ship and two South Korean vessels.