The United Nations has reportedly drawn up a peace plan to end the Saudi war on Yemen amid the failure of international diplomacy to halt the deadly aggression.

The peace plan calls on Yemen’s Houthi Ansarullah movement to renounce its ballistic missiles in return for an end to the bombing campaign by Saudi Arabia and a transitional governance agreement, Reuters reported Friday.

The draft document, cited by the news agency, has been drafted by the UN’s Yemen envoy Martin Griffiths. It says, “Heavy and medium weapons including ballistic missiles shall be handed over by non-state military actors in an orderly and planned fashion.”

The document calls for establishing an inclusive transition government, “in which political components shall be adequately represented,” in an apparent nod to the Houthis. The plan, however, offers no detail on how much representation the Houthis might receive in the transitional government.

The Houthis and their allies administer Sana'a and are unlikely to cede the capital without participation in a future government.

Previous efforts to end the Saudi war, which has left 600,000 Yemeni civilians dead and injured since 2015, have failed.

A source familiar with the plan said, “The intention is to link security and political aspects starting with a cessation of fighting ... then to move toward a withdrawal of forces and the formation of a national unity government.”

An Ansarullah official welcomed the UN plan, calling the ceasefire the first building block in the political process.

The official said the previous truces had failed, but “our optimism will be determined by how serious the other parties are of the UN role.”

The plan, which has not been made public, is the latest effort to end the war, which has led to one of the world’s worst humanitarian crises.

Anwar Gargash, the UAE's minister of state for foreign affairs, signaled Abu Dhabi's desire to support Griffiths' efforts but a spokesman for the so-called Saudi coalition declined to comment on the draft document, which he said he had not seen.

‘250,000 lives at risk in Hudaydah’

The UN proposal comes as Saudi-backed forces are about to begin an all-out assault on Yemen’s port city Hudaydah, through which the bulk of international humanitarian aid enters war-torn Yemen. Saudi Arabia and its allies have already placed an all-out embargo on other Yemeni border terminals.

A coalition spokesman said on Tuesday that allied forces were 20 kilometers (12 miles) away from the port.

UN Humanitarian Coordinator in Yemen Lise Grande warned, “A military attack or siege on Hudaydah will worsen the situation, impacting hundreds of thousands of innocent civilians.”

Lise Grande, the United Nations Humanitarian Coordinator for Yemen (Photo by AFP)

"In a prolonged worst case, we fear that as many as 250,000 people may lose everything — even their lives," Grande added.

Saudi Arabia and allies launched the war on Yemen in 2015 to reinstate a Riyadh-loyal former regime.

The war and blockade have caused famine across Yemen. The United Nations says a record 22.2 million Yemenis are in need of urgent food aid.

Several Western countries, in particular the United States and Britain, have been supplying the Saudis with advanced weapons and military equipment during the invasion.