The head of the United Nations food agency has accused Yemen’s Houthi rebels of diverting food from the country’s hungriest people and threatened to suspend food aid.

David Beasley, executive director of the World Food Programme (WFP), said the agency had found “serious evidence” that food supplies had been diverted in the capital, Sana’a and other Houthi-controlled areas in the country, which is in the midst of a four-year civil war. He called on the Houthis to implement agreements that would allow the UN agency to operate independently.

“If we do not receive these assurances, then we will begin a phased suspension of food assistance, most likely toward the end of this week,” Beasley said at the Security Council. “If and when we do initiate suspension, we will continue our nutrition program for malnourished children, pregnant women and new mothers.”

Beasley said the WFP has insisted on, and the Houthis finally agreed to, registration and biometric identification of beneficiaries as well as monitoring back in December, but the agency has faced blocks in implementing these measures since.

The humanitarian situation in Yemen is “catastrophic”, he said. The war has killed at least 70,000 people, left half the country’s 22 million population food-insecure, and sparked the worst cholera outbreak in modern history.

“Despite the immense suffering of 20 million Yemenis who do not have enough to eat, we continue to face fierce resistance to simply to do our job to keep people alive,” Beasley said.

The agency saw “early improvement” in early 2019, he said, but since then had received “concerning information”, including that 33% of respondents in Saada, a Houthi-controlled region in the north, had not received food aid, and that a “hotline” had detected 33 instances of misappropriation of food. In addition, 66% of staff monitoring visits had been blocked, he said.

Facebook Twitter Pinterest ‘Food assistance provided by the United Nations is being diverted in areas controlled by Ansar Allah at the expense of children, woman and men,’ said David Beasley, executive director of the World Food Programme. Photograph: Anadolu Agency/Getty

He said diversion of food aid was not limited to Houthi areas, but when the agency faced challenges elsewhere, it was met with cooperation from the government. Yemen’s internationally recognised government, which is backed by loyalist troops and the Saudi-led coalition, is based in the south.

Beasley had spoken out “very vocally and very critically” in 2017 about the blockade by the Saudi coalition forces on the city of Hodeida. At that time, he said, the Houthis expressed their gratitude that he had done so.

“I told them then, ‘This is nothing to do with you. This has everything to do with what’s right, everything to do with the World Food Programme, our humanitarian obligations and mandate to do everything in our power to reach those in need. To be neutral, to be impartial to be independent,’ and I told them, ‘If one day you cross this line, I’ll speak out to you, so do what’s right.’

“Today, I’m sad to say, the World Food Programme is being prevented from feeding the hungriest people in Yemen. Food assistance provided by the United Nations is being diverted in areas controlled by Ansar Allah at the expense of children, woman and men.”

Ansar Allah is the official name of the Houthi movement.

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In recent days, the Houthis have stepped up missile and drone attacks against Saudi cities, threatening a fragile peace agreement as tensions have risen between Iran and Gulf Arab states allied with the United States. Last month, the group carried out drone strikes on two Saudi oil pumping stations. Because of Iran’s support for the Houthis, the Saudis portray the conflict as a proxy war between Iran and its regional enemies, Saudi Arabia and the United Arab Emirates.

Western governments, including the UK and US, have faced ongoing criticism from rights groups for supplying the Saudi-led coalition, which intervened in Yemen’s war in 2015, with arms and logistical support for airstrikes.