Thousands stranded by airport power cut in Atlanta.

Travellers at the world’s busiest airport faced a second day of disruption on Monday after a power cut led to hundreds of cancellations.

Atlanta’s Hartsfield-Jackson airport lost power on Sunday, affecting tens of thousands of people.Passengers were left in darkened terminals or on board planes.

The airport is the world’s busiest, handling more than 250,000 passengers and almost 2,500 flights every day. But during its first hour of operation on Monday morning, fewer than a dozen commercial flights departed.

Power was restored overnight and a handful of passenger flights resumed just after 06:00 local time (11:00 GMT) on Monday.Hundreds of other flights, however, were cancelled.

A number of cargo flights had operated during the partial shutdown.

In a statement, the airport confirmed it had suffered a power cut shortly after 13:00 on Sunday.

Many flights scheduled to arrive from other airports were diverted elsewhere, or held at their departure airport.

Georgia Power, which supplies the airport’s electricity, said it believed a fire at an underground electrical facility had caused the power cut. Officials said a piece of its switchgear could have failed and started the fire, causing cable damage.

Atlanta’s mayor confirmed the fire’s cause was under investigation, and apologised to the thousands affected.

The local police department confirmed it had sent extra officers to help the airport with the situation.

About 30,000 passengers were reportedly affected by the power cut.