US airlines called off more than 1,000 flights on Sunday as crews were grounded amid surging COVID-19 infections, causing misery for thousands of Christmas travelers.

Iran PressAmerica: Commercial airlines had canceled 1,001 flights within, into, or out of the United States by mid-afternoon, according to a tally on flight-tracking website

It was the third straight day of traveling pain and further cancellations were likely as COVID-19 infections have soared, driven by the highly transmissible Omicron variant.

A total of 997 flights were scrapped on Christmas Day and nearly 700 on Christmas Eve. Thousands more were delayed on all three days.

The Christmas holidays, typically a peak time for travel coincided with a rapid spread of the Omicron variant.

Infections have risen sharply in many parts of the country, with New York state's health department warning on Friday that it recorded a "startling" four-fold increase in COVID-19 hospital admissions for children under 18 since the week beginning Dec. 5.

With the surge in infections, airlines have been forced to cancel flights with pilots and cabin crew needing to quarantine. Poor weather in some areas also contributed to the problems.

A White House official, who asked not to be named, said that despite the mess at some airports, "we're in a better place than last Christmas" and noted that "only a small percentage of flights are affected."

The US airports most heavily impacted by the cancellations were in Seattle, Atlanta, Los Angeles, Dallas-Fort Worth, and JFK International in New York.

Globally, FlightAware data showed that 2,617 flights were called off and more than 10,500 were delayed, as of 3:41 p.m. EST (2041 GMT) on Sunday.