The UN Security Council will meet Thursday for urgent talks following the launch of an offensive on the Yemeni port of Hodeida, a lifeline for aid, by government forces backed by the Saudi-led coalition, diplomats said.
Britain requested the meeting to be held behind closed doors at noon (1600 GMT) -- the second time this week that the council will have met on the crisis in Yemen.
The United Nations has raised alarm over the military operation, which could cripple deliveries of commercial goods and humanitarian aid to millions of people in Yemen, which is on the brink of famine.
British Foreign Secretary Boris Johnson warned in a statement that the military operation around Hodeida must not disrupt the flow of goods through the port.
"The coalition have assured us that they are incorporating humanitarian concerns into their operational plans. It is vital to maintain the flow of food, fuel and medical supplies into Yemen," said Johnson.
The Red Sea port, controlled by the Iran-backed Huthi rebels, serves as the entry point for 70 percent of the impoverished country's imports, but the coalition maintains that the rebels use it to smuggle weapons.
The UN special envoy for Yemen, Martin Griffiths, said he was continuing to hold negotiations on keeping Hodeida open and urged all sides to exercise restraint.
On Monday, the UN Security Council said it supported Griffiths' diplomatic efforts but did not specifically call on Saudi Arabia and the United Arab Emirates, whose troops are backing Yemeni forces, to refrain from attacking Hodeida.
The UN envoy had been pressing the Huthis to turn over the port to a UN-supervised committee that would allow shipments of vital supplies to continue to flow through it.
US Secretary of Defense Jim Mattis "strongly supports the efforts of the new UN Special Envoy, Martin Griffiths, to bring all sides of the conflict to the negotiating table," Pentagon spokesman Major Adrian Rankine-Galloway said Wednesday.
"We maintain that the port of Hodeida is critical to the delivery of humanitarian assistance to relieve the suffering of the Yemeni people," Rankine-Galloway said.
The British foreign secretary urged the Huthis to "not compromise port facilities or hinder the humanitarian response."
More than 22 million people in Yemen are in need of aid, including 8.4 million who are at risk of starvation, according to the United Nations, which considers Yemen to be the world's worst humanitarian crisis.
Since 2015, Saudi Arabia has been leading a military campaign to push back the Huthis after they seized the capital Sanaa in 2014 and restore the internationally recognized government to power.
The conflict has left nearly 10,000 people dead and tens of thousands wounded in what was already the Arab world's poorest country.