DUBAI: The United Nations has called on Yemen's internationally recognised government to allow the entry of communications equipment to the airport in the rebel-held capital Sanaa.

Yemen has been wracked by civil war since 2014, pitting the government, which is supported by a Saudi-led coalition, against the Iran-backed Huthis, who control much of the north.

Flights into the rebel-held capital have been largely halted by a Saudi-led blockade since August 2016, but there have been exemptions for aid flights that are a key lifeline for the population.

But Sanaa airport was closed for several days in December after the coalition pounded it with air strikes, accusing the Huthis of using it to launch missiles and drones at Saudi Arabia.

The Huthis reopened it on December 27.

"Closure of the airport to humanitarian flights severely undermines aid operations," the UN humanitarian coordinator for Yemen, David Gressly, said in a statement on Friday.

"I remain deeply concerned about any further disruptions."

Gressly welcomed the airport's reopening, but said communications equipment there had been found to be faulty.

"The Civil Aviation and Meteorology Authority (CAMA) in Sanaa deems the equipment obsolete," he said.

Yemen rebels announce temporary resumption of UN flights into Sanaa

According to Gressly, "UN humanitarian flight crews have reported at least 10 instances in which they were unable to contact the air control tower... or had unclear communications".

In order to rectify "a potentially dangerous situation", he urged Yemen's government to allow the import of new equipment.

He said the Saudi-led coalition "has not authorised the transfer, despite several requests from the United Nations, citing the need for Government of Yemen approval".

"The equipment is needed to ensure the safe use of Sanaa airport for humanitarian flights and, by extension, the continuation of the aid operation in Yemen," Gressly said.

The United Nations has described the situation in Yemen as the world's worst humanitarian crisis.

It has estimated that the conflict has claimed 377,000 lives by the end of 2021 through both direct and indirect impacts.