UN Special Envoy for Yemen Hans Grundberg said on Saturday that he has submitted a proposal to the Yemeni warring factions to prolong the ongoing truce for a long period.

"The United Nations is awaiting the response of the ­Yemeni parties to our proposal," he said in an interview with the Al Jazeera news channel, stressing the need for constructive cooperation between all sides involved.

"We hope to reach a final solution and a permanent ceasefire that ends the war in ­Yemen." 

In the previous week, ­Yemen's Presidential Leadership Council (PLC) Chairman Rashad al-Alimi said that his government welcome renewing the UN-brokered truce, which will expire within a couple of days.

The PLC chief called for opening roads and lifting the siege imposed by the Houthis on the Yemeni city of Taiz as a condition to go forward with extending the truce.

However, the Houthis in Sanaa have said they were still studying everything proposed regarding the truce, calling for lifting the restrictions imposed by the Saudi Arabia-led coalition on Yemen's airports and ports.

The ongoing truce, which has been largely held, went into force for the first time on April 2 and was later renewed twice through October 2.

Yemen has been mired in a civil war since late 2014 when the Iran-backed Houthi militia seized control of several northern provinces and forced the Saudi-backed Yemeni government out of the capital Sanaa.

The war has killed tens of thousands of people, displaced 4 million, and pushed the country to the brink of starvation.