The UN envoy to Yemen called for the extension of a five-day humanitarian ceasefire due to end Sunday, expressing hope it could become permanent.

"I call on all parties to renew their commitment to this truce for five more days at least," Mauritanian diplomat Ismail Ould Sheikh Ahmed told a meeting in the Saudi capital.

"This humanitarian truce should turn into a permanent ceasefire," he said.

The ceasefire, which began late Tuesday, has been "extremely important to give Yemenis a break allowing in medical aid and basic supplies," the envoy said.

But he pointed out that "most Yemenis have not yet managed to get their hands on" the aid that has been channelled to the war-wracked country.

The United Nations has expressed deep concern about the civilian death toll from the Saudi-led bombing as well as the humanitarian impact of an air and sea blockade imposed by the coalition.

It says more than 1,500 people have died in the conflict since late March.