Fears over massive civilian casualties, and a breakdown in aid supplies if latest Arab coalition offensive against Houthis' main port goes unchecked.
The UN security council meets behind closed doors on Thursday at Britian's request as alarm grows over the Saudi-led Arab coalition's latest offensive against Iranian-backed Houthi rebels.
Operation "Golden Victory" aims to wrest control of Yemen's biggest port, Hodeida, from Houthi control, but the fighting risks cutting off the vital aid that flows through the port, keeping millions of Yemenis alive.
For the last two days coalition naval forces and aircraft have been bombarding rebel positions, and some 21,000 troops backed with armour have been postioning themselves for a ground assault, and artillery fire has added to the growing civilian panic.
Thousands of people are attempting to escape the port for the surrounding countryside, fearing a massacre, although the coalition says it will only occupy the port and will not deploy in the town itself to avoid mass casualties.
Many people crammed into the port, including large numbers of women and children, have already fled fighting elsewhere.
The coalition says it wants to deny the Houthis their main supply line, and end alleged racketeering of aid supplies.