Yemen's Iran-allied Houthis said Saudi Arabia was attacking the Yemeni capital Sanaa on Tuesday after a Saudi-led coalition warned civilians to stay away from an oil depot on the city's outskirts, part of a rapidly escalating war between the sides.

Saudi-backed Yemeni government forces have secured effective control of the Bab el-Mandeb Strait, Yemen's Information Minister Moammar al-Eryani told Reuters on Monday, though fighting continues with Houthi forces in the area.

Saudi Arabia is planning an offensive against Iran-backed Houthi militants in Yemen, with options being considered including a coastal push to secure the Red Sea shipping route or an assault on multiple fronts, regional and Western officials told Reuters.