SANAA, Yemen (AP) — Yemen's Houthi rebels began on Saturday a long-delayed withdrawal of their forces from the key port city of Hodeida, the group said, following the terms of a cease-fire. The U.N.-brokered agreement is aimed at alleviating the world's worst humanitarian crisis.

Mohammed Ali al-Houthi, the head of the rebels' Supreme Revolutionary Committee, said the pullout from Hodeida, as well as the two smaller ports of Salif and Ras Issa, started at 10 a.m. (0700 GMT).

Sadek Dawad, a government negotiator, said that he welcomed the "first step of the first phase of redeployment" of rebel forces in the area. He urged the U.N. to verify and watch the pullout. He also called for the removal of land mines laid by the Houthis.

The Houthi-run al-Masirah TV channel said U.N. observers are monitoring the forces' withdrawal.

Hodeida is the main international entry point for 70 percent of imports and humanitarian aid to Yemen, where the four-year civil war has killed an estimated 60,000 people and pushed much of the country to the brink of famine. Nearly two thirds of Yemenis are in need of some sort of aid and 3 million displaced. Thousands have died of malnutrition, preventable diseases and epidemics.

A cease-fire brokered by the U.N. in December in Sweden called for the mutual withdrawal of rebel and government forces from Hodeida, and the two smaller ports in the province.

The bloody conflict erupted in September 2014, when Shiite Houthi rebels swept into the capital city of Sanaa. A Saudi-led coalition rapidly intervened to back the government of President Abed Rabbo Mansour Hadi.

An official from the internationally recognized government said that the government will meet with the head of the U.N. operation monitoring the cease-fire, Lt. Gen. Michael Lollesgaard, later on Saturday. The official spoke on condition of anonymity as he was not authorized to speak with the media.

Lollesgaard said Friday that the Houthis' withdrawal from the three ports marked the first practical step toward realizing the cease-fire.

He added that the Houthis must commit to following fully through with the redeployment, which is expected to take place over three days.

He said the full implementation of the Hodeida deal remains instrumental to ensuring life-saving humanitarian access into Yemen.

The U.N.-brokered deal was vague on who will control Hodeida's strategic ports after the rebels withdraw, saying a "local force" would take over without specifying further.

The pullout was scheduled to take place two weeks after the cease-fire went into force on Dec. 18. The deadline was missed as the government and the rebels haggled over the interpretation of the deal.

The agreement in Sweden also included a prisoner exchange between the two sides, which has yet to be carried out.

Magdy reported from Cairo.