CAPITALS — Saudi-backed government forces have begun an assault on the key Yemeni port of Hudaydah, which is held by rebels.
The port is the main point of entry for aid for people in rebel-held areas and agencies have warned of a humanitarian catastrophe if it is attacked.
About eight million people in the war-torn country are at risk of starvation.
Bombing started after Iranian-backed Houthi rebels ignored a deadline set by the government to withdraw by midnight (21:00 GMT on Tuesday).
The conflict has raged since late 2014, when the Houthis and allied forces seized north-western parts of Yemen, including the capital Sanaa, and eventually forced President Abdrabbuh Mansour Hadi to flee abroad.
Alarmed by the rise of a group they saw as an Iranian proxy, Saudi Arabia and eight other Sunni Arab states launched a military campaign in March 2015 to restore Mr Hadi's government.
The conflict has created the world's largest food emergency.