The said it has further reduced rations in , where millions face hunger, due to critical funding gaps, global inflation and knock-on effects of the conflict.
The United Nations body feeds 13 million people a month in Yemen, where the economy has been wrecked by seven years of war. The country of some 30 million people imports most of its food.
"We are now being driven to scale back that support for 5 million of those people to less than 50% of the daily requirement, and for the other 8 million to around 25% of the daily requirement," WFP said in a Twitter post on Sunday.
"Resilience and livelihood activities, and school feeding and nutrition programs, will cease for 4 million people, leaving assistance available for only 1.8 million people."
The WFP had since January reduced rations for 8 million people and warned in May that it could soon have to make further cuts after raising only a quarter of the $2 billion it needs for Yemen this year from international donors.
The number of people living in near-famine conditions in the Arabian Peninsula country is expected to rise to seven million in the second half of 2022 from around five million.
Disruption to global wheat supplies due to the Ukraine war and a wheat export ban by India risk deepening Yemen's hunger crisis and pushing up food price inflation, which had already doubled in just two years in some parts of the country.
The planning minister in the Saudi-backed government warned on Friday that Yemen's wheat stockpile could be depleted by mid-July and urged European Union states to help secure new markets to replace Ukrainian and Russian wheat.
Yemen is facing a foreign reserves shortage and a serious devaluation of the currency in some regions.
Local traders are also struggling to import flour, rice, sugar and petroleum products due to high prices, the vice-chairman of the Federation of Yemen Chamber of Commerce and Industry, Abu Baker Baobaid, told Reuters.