UNITED NATIONS, April 17 (Xinhua) -- UN Undersecretary-General for Humanitarian Affairs Mark Lowcock on Tuesday expressed concern about insufficient commercial imports, particularly food, to Yemen.

"We remain very concerned about commercial imports through all of Yemen's ports, most particularly (the Red Sea ports of) Hudaydah and Saleef," Lowcock told the Security Council.

Before the war, Yemen relied on imports to cover 90 percent of staple food and nearly all its medicine and fuel needs, he said. "Commercial shortages and delays at ports have led to sharp increase in the price of food and household necessities. Ports are the lifeline of Yemen."

Price increases, especially of food, are forcing hundreds of thousands of destitute families to turn to humanitarian assistance for their very survival, he said.

The United Nations is encouraging all those concerned to accelerate the normalization of commercial shipments into Hudaydah and Saleef, as well as to Yemen's other ports, he said. "We are worried that shipping companies are reluctant to enter Yemeni waters."

The reasons are related to problems with foreign exchange and the banking sector as well as the ports, but the result is that insufficient food is being imported, he explained.

Lowcock also voiced concern over the fact that Sanaa airport remains closed to commercial traffic. The closure of the airport is preventing thousands of critically ill patients from traveling abroad to seek treatment unavailable in Yemen, he said. Military activities conducted in the proximity of the airport over the last month have affected humanitarian flights.

Yemen, which has been in war since 2015, remains the world's worst humanitarian crisis, he said. Three quarters of the population, or more than 22 million people, urgently require some form of humanitarian help, including 8.4 million people who struggle to find their next meal, said Lowcock.