UNITED NATIONS (Reuters) - A redeployment of forces in Yemen’s Hodeidah by the warring parties could start “possibly even today or tomorrow,” United Nations Yemen envoy Martin Griffiths told the U.N. Security Council on Tuesday.

FILE PHOTO: People ride a motorbike on a street in Hodeidah, Yemen December 15, 2018. REUTERS/Abduljabbar Zeyad -/File Photo

The Iran-aligned Houthi movement and the Saudi-backed government agreed at talks in Sweden in December to withdraw troops by Jan. 7 from the Red Sea city under a truce aimed at averting a full-scale assault on the port and paving the way for negotiations to end the four-year war.

But the pact stalled over control of Hodeidah, a lifeline for millions facing famine. After weeks of diplomacy, the United Nations said on Sunday the parties had reached agreement on phase one of a troop redeployment.

“With the beginning, possibly even today or tomorrow, of the implementation of that part of the Hodeidah agreement we now have the opportunity to move from the promise made in Sweden to hope now for Yemen,” Griffiths told the 15-member council.

Under phase one, the Houthis would withdraw from the ports of Hodeidah, Saleef, used for grains, and Ras Isa, used for oil. This would be met by a retreat of Saudi-led coalition forces from the eastern outskirts of Hodeidah, where battles raged before a ceasefire went into effect on Dec. 18.

Houthi spokesman Mohammed Abdulsalam said late on Monday the withdrawal of troops from the ports could be implemented in the two days following Sunday’s agreement but the group was waiting to hear from the United Nations.

However, the Yemeni government believes implementation of phase one should only start when both sides agree on the local authority that will run the ports and the city under the Stockholm agreement, said Sadeq Daweed, a government spokesman.

Two sources involved in the negotiations, who declined to be named due to the sensitivity of the discussions, said on Monday that both sides had yet to agree on a mechanism for local forces to take over security at the ports and city.

Griffiths said phase one of the redeployment of forces would “facilitate humanitarian access to the Red Sea Mills.”

The World Food Program grain stores at the Red Sea Mills are enough to feed 3.7 million people for a month and have been inaccessible for more than five months. The United Nations has warned the food is at risk of rotting.

Griffiths urged the parties to agree on the details of the second phase of troop withdrawals, which entails full redeployment of both parties’ forces in Hodeidah province.

The Hodeidah truce has largely been respected but there have been intermittent skirmishes in flashpoints on the city’s edges.

The Sunni Muslim alliance led by Saudi Arabia and the United Arab Emirates intervened in 2015 to restore the internationally recognized government that was ousted from power in Sanaa in late 2014.

The conflict, which has killed tens of thousands, is widely seen in the region as a proxy war between Saudi Arabia and Iran. The Houthis deny receiving help from Tehran and say their revolution is against corruption.