Iran-allied Shiite Houthi rebels in Yemen are preventing aid workers from accessing aid for millions of Yemenis, putting the food “at risk of rotting” while an estimated 20 million people in the country find themselves on the brink of starvation, the United Nations warned Monday.

The at-risk grains stored in the Houthi-held port city of Hodeida [or Hudaydah] is enough to feed 3.7 million people for a month and have been inaccessible for more than five months, the U.N. revealed in a press release issued Monday. The international body believes up to 20 million of the country’s residents are facing “severe acute food insecurity.”

“With enough food to feed 3.7 million people for a month, the grain stored in the [Hodeida] mills could help the [U.N.’s] World Food Programme (WFP) scale up food assistance to nearly 12 million people across the war-torn country; a 50 percent increase on 2018,” the international body acknowledged.

In a joint statement, Mark Lowcock, the U.N. emergency relief chief, and Martin Griffiths, the international body’s special envoy to Yemen, beseeched the warring parties for access to the food.

“We emphasize that ensuring access to the mills is a shared responsibility among the parties to the conflict in Yemen. With safe, unfettered and sustained access, the United Nations can make this urgently needed food available to people in need,” the U.N. officials declared.

Since March 2015, a Sunni Saudi Arabia-led coalition has been fighting Shiite Iran-backed Houthi rebels to restore the government of the internationally recognized Yemeni President Abd Rabbu Mansour Hadi. Most of northern Yemen, including the capital of Sanaa and the port city of Hodeida, reportedly remains under the control of the Houthis.

“Until now … forces affiliated with the Houthi movement, or Ansar Allah, which controls the vital port of Hudaydah, have not allowed the UN to cross front lines to access the mills on the outskirts of the city,” the U.N. noted on Monday.

The U.N. Security Council is reportedly pushing for the withdrawal of fighters from the port city and the stabilization of the fragile ceasefire.

“Accessing the 51,000 tons of U.N. wheat and milling equipment at the frontline flashpoint is a key aim of ongoing peace talks,” Reuters reported.

Early this month, the U.N. Security Council urged the warring parties in Yemen to pull out of Hodeida “without further delays,” Voice of America (VOA) revealed, adding:

The warring parties were meant to withdraw their forces by Jan. 7 as part of efforts to avert a full-scale assault on Hodeida, but have failed to do so as the Iranian-aligned Houthi group and the Saudi-backed government disagree on who should control the city and ports.

The Saudi-led coalition maintains that the Houthis must abandon Hodeida as a precondition for a peace deal, a proposal rejected by the Shiite rebels.

A truce reached by the warring parties in December has mainly held in the port city, but confrontations have reportedly increased in recent weeks.

Yemen is home to the world’s worst humanitarian crisis triggered by the war between the Saudi-led coalition and Shiite Houthis.

For about a year, the Saudi-led coalition has been trying to push the Houthis out the port city of Hodeida, which reportedly allows Iranian military supplies and funding to reach the rebels.

Yemen, considered the most impoverished in the Middle East, heavily relies on imports for almost 90 percent of its food and the vast majority of aid.

Hudaydah is a strategically important city that is considered the lifeline for Yemen as the country’s largest and most vital port where most of the aid and food comes through.

Echoing other assessments, Save the Children Yemen, a major aid agency in the country, reportedly warned last week that continued fighting in Hodeida could plunge Yemen further into famine.