UNITED NATIONS, Feb. 19 (Xinhua) -- The UN special envoy to Yemen reported "significant progress" by Yemen's warring parties in implementing the Stockholm Agreement, a UN spokesman said on Tuesday.

"Martin Griffiths briefed the Security Council by video conference this morning (Tuesday) on what he called the significant progress made in implementing the agreements reached in Stockholm," said Stephane Dujarric, the spokesman for UN Secretary-General Antonio Guterres.

Griffiths "welcomed the agreement on the redeployment of the parties -- first from Saleef and Ras Issa and then from the port of Hodeidah -- as a first step," Dujarric told reporters at a regular briefing. "Griffiths said that despite deadlines being missed, the parties have constantly showed their commitment to the agreement."

The spokesman added that Griffiths continued to work on a prisoner swap. "The watchword for the process is a release of 'all for all'."

Dujarric said Griffiths "expressed hope that the release of the first batch of prisoners could take place soon."

Hodeidah is Yemen's key Red Sea port city, with Saleef for handling grain and Ras Issa for oil. They have been held by the Houthi rebels with fighting blocking humanitarian access.

The United Nations and its humanitarian partners appealed for 4.2 billion U.S. dollars to aid 19 million Yemenis in need, said Dujarric.

Meanwhile, UN Under-Secretary-Geneneral for Humanitarian Affairs and Emergency Relief Coordinator Mark Lowcock said in his briefing to the Security Council Tuesday that about 80 percent of the Yemeni population, or about 24 million people, need humanitarian assistance and protection, and that some 20 million people need help to secure food, including 10 million on the brink of famine.

Lowcock expects current resources to be used by the end of March, just six weeks from now, noting next week's meeting in Geneva on funding for Yemen and urged UN member states to attend the meeting at a senior level and, of course, to pledge generously.

A deal reached in Stockholm in December 2018 says the Yemeni government and Houthi rebels should withdraw troops from the city of Hodeidah and ports of Hodeidah, Salif and Ras Issa.

Since 2015, nearly 15 percent of the people in Yemen have been forced to flee their homes, the vast majority of whom are still displaced, according to the United Nations.