The Iran-backed Houthi movement in Yemen warned allies of Israel on Wednesday that their shipping in the Bab al-Mandab Strait at the entrance to the Red Sea is a "legitimate target."

The warning comes after the Houthis on Sunday seized an Israel-linked cargo vessel, opening a new dimension in the Gaza war between Israel and the Palestinian Islamist group Hamas.

Helicopter-borne troops seized the Galaxy Leader and its 25 international crew, days after the Houthis threatened to target Israeli shipping because of the war.