UN aid flights into Yemen's rebel-held capital Sanaa have been halted by air strikes carried out by the Saudi-led coalition which supports the government, an airport official said Tuesday.

Because of coalition air strikes targeting the Huthi rebels, "the airport is no longer able to receive aircraft operated by the United Nations or international humanitarian organisations", the official told AFP.

Flights into Sanaa airport 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.

The airport official, who asked not to be identified, called on the United Nations to secure a halt to the raids so that the airport could resume operations.

On Monday evening, the coalition said it had carried out "a limited number of precision strikes on legitimate military targets in Sanaa international airport".

"The operation was mounted in response to the threat and use of airport infrastructure to carry out cross-border attacks," it said in a statement carried by the official Saudi Press Agency.

Coalition aircraft hit six targets in the airport, including sites used to "control attacks by drones loaded with explosives" or to "train terrorist elements" for such operations, the statement said.

The coalition insisted that its strikes were "in accordance with international humanitarian law" and should have no impact on the airport's operational capacity.

Khaled al-Shayef, director general of Sanaa airport, told AFP that the "health quarantine quarters and warehouses to store export and import goods were destroyed".

A metal hangar and cement structures near an air traffic control tower were also destroyed, an AFP correspondent reported.

The Norwegian Refugee Council urged both sides to work with the UN to reopen the airport for humanitarian and commercial flights.

"Aid delivery to the airport is now at a standstill. We urge both the authorities in Sanaa and the Saudi-led coalition to keep Sanaa airport out of the crossfire and to ensure that it can function again for medical and commercial flights," NRC country director Erin Hutchinson said in a statement.

A UN humanitarian flight brings Yemeni twins Mohamed and Ahmed back to the rebel-held capital Sanaa last month following successful surgery in Jordan to separate them after they were born conjoined last year
A UN humanitarian flight brings Yemeni twins Mohamed and Ahmed back to the rebel-held capital Sanaa last month following successful surgery in Jordan to separate them after they were born conjoined last year UNICEF via AFP / Fuad MOOHIALDIN

The rebels have repeatedly launched missile and drone strikes against neighbouring Saudi Arabia, targeting the kingdom's airports and oil infrastructure.

They have intensified their strikes on the kingdom in recent months.

In August, a drone hit Abha international airport, wounding eight people and damaging a civilian plane.

And in October, Saudi state media reported that 10 people were injured in a drone attack on a civilian airport in the Saudi Red Sea city of Jeddah.

Saudi Arabia and its allies intervened in the Yemeni civil war in 2015, shortly after the rebels seized the capital Sanaa.

The conflict has led to what the United Nations has called the world's worst humanitarian crisis. Tens of thousands of people -- most of them civilians -- have been killed in the war.

More than 80 percent of the population of around 30 million require humanitarian assistance.

A UN Development Programme report last month said the war will have claimed 377,000 lives by the end of the year through both direct and indirect impacts.

Nearly 60 percent of deaths will have been caused by consequences such as lack of safe water, hunger and disease, it said, suggesting that fighting will have directly killed over 150,000 people.

While the UN and Washington are pushing for an end to the war, the Huthis have demanded an end to the coalition air blockade of Sanaa airport before any ceasefire or negotiations.

"Last night's attacks on Sanaa airport will not change much for the millions of impoverished Yemenis who were already cut off from the rest of the world," Hutchinson said.

"But it should serve to open the world's eyes to the madness that is punishing millions of civilians who have no say in this conflict."