CAIRO -- Yemen's warring parties have agreed on the first stage of a mutual pullout of forces from the key port city of Hodeida, a humanitarian aid lifeline that had been blocked by fighting, the United Nations said.

A UN statement late Sunday said the agreement by a committee -- which includes members of Yemen's internationally recognized government and their adversaries, the Shiite Houthi rebels -- came after two days of meeting behind the Hodeida front line.

The warring sides agreed in Sweden in December to confidence-building measures, including a cease-fire in Hodeida and the exchange of thousands of prisoners. But the implementation of those deals has been slow and marred by violence.

The UN says the committee, led by Danish Lt. Gen. Michael Lollesgaard, plans to reconvene within a week.

The statement said both sides "made important progress on planning for the redeployment of forces as envisaged in the Hodeida agreement."

Meanwhile, UN envoy Martin Griffiths arrived Sunday in the Yemeni capital, Sanaa, to discuss the "complex situation" in and around Hodeida. Griffiths met with Houthi rebel leader Abdul-Malek al-Houthi.

The agreement in Sweden was seen as a key step in attempts to end the conflict in Yemen, which began with the 2014 takeover of Sanaa by the Iranian-backed Houthis who toppled the government of President Abed Rabbo Mansour Hadi. A Saudi-led coalition allied with Hadi's forces intervened and has been fighting the Houthis since 2015.

The fighting in the Arab world's poorest country has taken a terrible toll on civilians, with thousands killed and a catastrophic humanitarian crisis underway. Millions suffer from food and medical care shortages and the country has been pushed to the brink of famine.