Yemen's Houthis blocked a food shipment earmarked to feed 100,000 families in the impoverished nation that has been pushed to the brink of starvation by more than four years of war.

A World Food Programme (WFP) spokesperson, who spoke on condition of anonymity, said on Tuesday the aid was prevented from reaching civilians after the UN body partially suspended relief efforts last week, accusing the Houthis of looting it.

The suspension follows a dispute over control of biometric data that WFP uses to ensure food aid was not being diverted from its intended recipients.

The Houthis, who control northern Yemen, said the WFP's insistence on controlling the data breached Yemeni law and launched a fierce media campaign against the UN organisation, accusing it of sending spoiled food.

The WFP spokesperson said the Houthis blocked more than 8,000 tonnes of flour that was sent from the Red Sea port of Hodeida. The Houthis claimed it was contaminated with dead insects.

A subsequent check of the cargo, now docked in Oman, showed it was clean.

'Funding military operations'

UN food chief David Beasley said on Friday that WFP estimated at least 10 percent of the $175m in monthly food aid it provided was being diverted in Houthi areas to help fund the conflict.

Saudi Arabia and its allies intervened in Yemen in 2015 to try to restore the government of President Abd-Rabbu Mansour Hadi after the Houthis seized much of the country, including the capital Sanaa.

Both parties in the four-year conflict, widely seen in the region as a proxy war between Saudi Arabia and Iran, have used access to aid and food as a political tool.

"At this stage, you can clearly say the humanitarian system is funding military and political operations. We are independent, neutral, impartial and if we can can't guarantee that we shouldn't be there," Beasley said.

"The entire humanitarian system is at stake here."

The Yemen conflict has killed tens of thousands of people since March 2015, according to the World Health Organization.

Fighting has triggered what the UN describes as the world's worst humanitarian crisis, with 3.3 million people displaced and 24.1 million - more than two-thirds of the population - in need of aid.

-Agencies