Washington, Dec 28 (IANS): As a deadly winter storm continues to wreak havoc across the US, nearly 4,900 flights were cancelled, with more than 4,400 others delayed in the last 24 hours, the media reported.

Southwest Airlines was the hardest hit as it cancelled over 60 per cent or 2,500 of its flights on Tuesday, reports the BBC.

More than 3,500 flights scheduled to leave Wednesday have already been cancelled, according to flight tracking service FlightAware.

Since the storm began on December 22, nearly 20,000 flights have been cancelled across the US, the service added.

The US Department of Transportation (DOT) has said that it is "concerned by Southwest's unacceptable rate of cancellations and delays (and) reports of lack of prompt customer service".

In a tweet on Tuesday, President Joe Biden said that his administration is "working to ensure airlines are held accountable" for disruptions.

He urged passengers to check whether they are entitled to compensation.

Southwest, for its part, has repeatedly apologised and said the disruptions caused by the winter weather are "unacceptable".

On its website, the airline said that it will honour "reasonable requests" for reimbursement for meals, hotel and alternate transportation for those who have had flights cancelled or delayed between December 24, 2022 and January 2, 2023, the BBC reported.

With flight cancellations and delays continuing, thousands of passengers have been left at airports across the US as they attempt to re-book flights or make alternative travel arrangements.

Passengers in major cities including Washington D.C., Denver and Chicago have reported hours-long queues to speak to customer service representatives.

More than 60 people have so far been reported dead as a result of the winter storm, including at least 28 in Buffalo, New York.