A sign is seen on a wall during a protest against a Saudi blockade of Yemen's ports, outside the United Nations' offices in Sanaa, Yemen October 19, 2015. [Photo/Agencies]

UN aid chief Stephen O'Brien said in August that coalition air strikes on Yemen's Red Sea port of Hodeida could worsen the humanitarian crisis. On Monday, as he sat next to Al Rabeeah at a news conference, he said the port had been compromised.

"The first and the best humanitarian response is for the fighting to stop and that is what is urged at all times on all the parties engaged," O'Brien said.

In a bid to increase commercial shipments to Yemen, he said the United Nations had come up with its mechanism to inspect any suspicious vessels but was still trying to raise the $8 million needed for it to be operational.

Yemen only received 1 percent of its monthly commercial fuel needs in September, the United Nations said. Access to water usually depends on fuel-powered pumps, while hospitals struggle to operate without fuel and aid cannot be delivered.