Yemen's Houthi group and the party of the former president have accepted a peace plan brokered by the United Nations in talks in Oman, paving the way for resuming negotiations to end months of conflict in the country.

Both groups have said on Wednesday that they had officially on Wednesday notified UN chief Ban Ki-moon that they were ready to join talks on a settlement based on a seven-point peace plan proposed by the UN in talks in Oman last month.

Aid agencies and the UN have raised alarm over the human cost of the war, both from fighting that has claimed over 5,000 lives and from a blockade by the Saudi-led coalition supporting Hadi that they say has brought Yemen close to famine.

Citing allegations of war crimes, the rights group Amnesty International on Wednesday called for states including the United States and United Kingdom to stop arming the Saudi-led coalition, which has been bombing Yemen for over six months.

In his letter dated on October 3, Houthi spokesman Mohammed Abdul-Salam confirmed that his group and others allied to it backed the seven-point plan.

"The Security Council supports a political settlement for the Yemen crisis and the return to the talks with no preconditions, and so do we," the letter added.

Former President Ali Abdullah Saleh's General People's Congress (GPC) party also accepted the plan. "An official source at the General People's Congress reiterated the party's fast position on ending hostilities and raising the blockade and on a peaceful solution to Yemen's crisis," it said in a statement.

The Saudi-led coalition and President Abd-Rabbu Mansour Hadi view the Houthis as proxies for non-Arab Iran and regard Saleh as a spoiler trying to undermine a political accord that allowed him to step down following months of protests in 2011.

Hadi had previously refused a UN invitation to peace talks in the region, demanding that the Houthis publicly accept the UN Security Council resolution.

In its report, Amnesty said: "Damning evidence of war crimes by the Saudi Arabia-led coalition, which is armed by states including the USA, highlights the urgent need for independent, effective investigation of violations and for the suspension of transfers of certain arms."

It urged an end to the sale of warplanes, helicopters and bombs, especially internationally-banned cluster bombs. A spokesman for the Saudi-led coalition did not immediately respond to a Reuters request for comment.

Gulf-backed forces have in recent weeks pushed the Houthis and Saleh's forces out of Yemen's second city Aden and retaken swathes of the south.-Reuters