Passengers of United Airlines in the US have faced delays after the airline temporarily halted flights at major airports over a "technology issue".

A ground stop was issued for the company's mainline flights from departure airports, causing issues at airports including Chicago, Denver, Houston, San Francisco and New Jersey.

The firm said at about 22:00 EDT on Wednesday (02:00 GMT on Thursday) that flights were no longer grounded, but that disruption was ongoing.

"The underlying technology issue has been resolved, and, while we expect residual delays, our team is working to restore our normal operations," the airline's statement at the time read.

Over 700 United flights had been delayed as of 21:00 EDT (02:00 BST), according to flight tracking site FlightAware.

Flights that were already in the air during the ground stop were able to continue to their destinations.

Regional flights were not impacted, but United warned that they could be delayed because of traffic jams from the ground stops.

One passenger, Jessica Jeffers, told CNN that she had been stuck for two hours on a plane in Denver waiting to go to Newark, New Jersey.

"It's been pretty rough over here," she said.

Other passengers complained on social media about being stranded on tarmacs for hours as they waited for news.

The BBC's US partner network, CBS News, reported that the airline was treating the incident as a preventable delay, meaning it would cover certain expenses incurred by passengers.

Transportation Secretary Sean Duffy said he had been briefed by United, and that the issue was "unrelated to the broader air traffic control system" in the US. (BBC)