The humanitarian crisis in Yemen, already the world's worst, will deteriorate in 2019, the U.N. said yesterday, warning that the number of people needing food aid is set to jump by 4 million. The warning came amid the U.N. sponsored peace push. "The country with the biggest problem in 2019 is going to be Yemen," the United Nations Office for the Coordination of Humanitarian Affairs' (OCHA) chief, Mark Lowcock, told reporters in Geneva.

He said that in 2017, the U.N. was providing food assistance to 3 million people every month. That figure rose to 8 million per month this year and is expected to hit 12 million in 2019, Lowcock added. The Yemeni government backed by the Saudi-led coalition and Houthi rebels said yesterday they had agreed to swap hundreds of prisoners in another boost to U.N. efforts to convene new peace talks later this month.

The deal was struck by U.N. envoy Martin Griffiths, who was in the rebel-held capital Sanaa yesterday for meetings already buoyed by the evacuation of 50 wounded Houthi insurgent fighters for treatment in neutral Oman on Monday, a key rebel precondition for the talks. The envoy is seeking to convene peace talks in Sweden, perhaps as early as this week, after a previous attempt collapsed in Switzerland in September.

Yemen has been wracked by conflict since 2014, when Shiite Houthi rebels overran much of the country. Saudi Crown Prince Mohammed bin Salman (MBS), the former defense minister, and Saudi Arabia's allies launched Operation Decisive Storm in March 2015. Civilians have borne the brunt of the conflict, which has killed over 10,000 people and sparked the world's worst humanitarian crisis.