Operations at Yemen's lifeline port of Hodeidah have dropped by almost 50 percent over the past two weeks, with shipping companies deterred by insecurity in the flashpoint Houthi-held city, according to the United Nations.
Saudi Arabia and UAE-led forces are fighting to overthrow the rebels that have taken over most of northern Yemen, including the capital, Sanaa.
As 70 percent of imports come in through the vital Hodeidah port, a drop in the arrival of wheat and other supplies would affect food stocks in Yemen where 14 million people are facing possible starvation after nearly four years of war, the UN's World Food Programme said on Tuesday.
"WFP is very concerned about a nearly 50 percent decrease in operations at Hodeidah port over last two weeks," Herve Verhoosel, a spokesperson for the agency, told reporters in Geneva.
"Shipping companies appear to be reluctant to call to Hodeidah port because of the high levels of insecurity in the city," he said.
The WFP, which provides rations to eight million Yemenis each month, has been trying to scale up its efforts to avert famine.
It has two more months worth of food stocks in the impoverished country, Verhoosel said.
"Any disruptions to the port operations would hamper humanitarian efforts to prevent famine as well as increase food prices in markets even further, making it extremely difficult for the majority of Yemenis to feed their families," he added.
On Monday, a single vessel was at Hodeidah port, which was "not normal" for a port whose current offloading capacity is for seven vessels, he said, adding: "We need to reassure the private sector to say 'come back to the port'."
UN envoy for Yemen Martin Griffiths, who was in the Saudi capital, Riyadh on Monday, is seeking a role for the world body in supervising the port.
He continues his consultations ahead of peace talks planned in Sweden next month, UN spokesperson Rheal LeBlanc said.
After the Houthis swept through most of the country in 2014 and deposed its government, a Saudi-UAE military coalition, backed by the US, intervened in 2015 with a massive air campaign aimed at reinstalling the government of Abd-Rabbu Mansour Hadi.
Since then, data collected by Al Jazeera and the Yemen Data Project has found that more than 18,000 air raids have been carried out in Yemen, with almost one-third of all bombing missions striking non-military sites.
Weddings, funerals, schools and hospitals, as well as water and electricity plants, have been hit, killing and wounding thousands.
Tens of thousands of people have been killed in the war, and according to Save the Children, as many as 85,000 children under five "may have died from extreme hunger" or disease since 2015.