Authorities in Nepal have announced that the runway of the country's main international airport is to be closed to large aircraft, after it sustained damage from an influx of large planes carrying aid to assist in earthquake rescue and recovery efforts.

A Nepalese official told NBC News that aircraft weighing over 196 tons were being told not to land at Tribhuwan International Airport (TIA).

"The notice [was] issued after technically assessing that the overuse of the runway by unscheduled flights is damaging it," Hari Odiani of Nepal's Ministry of Foreign Affairs said.

Despite the setback, the UN coordinator for Nepal Jamie McGoldrick, told the Associated Press that the bottlenecks in aid delivery were slowly disappearing.

"I think the problem is there, but it's actually diminishing," he said, adding the Nepalese government eased customs and other bureaucratic hurdles on humanitarian aid following complaints from the U.N.

The decision to limit incoming aircraft was taken after at least three cracks appeared on the airstrip. More than 300 rescue flights, including 150 chartered, have landed at TIA since the earthquake rattled the country on April 25, the Kathmandu Post reported.

Birendra Shrestha, the manager of TIA, told the Rakyat Post that the runway was built to handle only medium-size jetliners -- not the large military and cargo planes that have been flying to the airport since the magnitude-7.8 earthquake struck.

Airport sources told the paper that many countries, including the U.S. and Canada, have been asking “to lift the restriction”.

The U.S. military has announced that troops and equipment are en route to Nepal, with the first contingent expected to arrive Sunday.

The death toll from the quake, which is the strongest to hit Nepal in decades, has now risen to 7,057 people.