US carrier Alaska Airlines said early on Friday it had restored operations following a technology outage that grounded flights across all airports and led to the cancellation of more than 229 flights.

"We are working to get our operations back on track as quickly and safely as possible," the airline said, adding that further flight disruptions were likely.

Alaska Air Group said it does not have an estimate yet of the financial impact the disruption may have on its fourth-quarter results.

It requested a temporary ground stop on Thursday evening, which also affected Horizon Air, a subsidiary of Alaska Airlines, according to a Federal Aviation Administration advisory.

The airlines said the halt was lifted at 11.30pm local time on Thursday or 2.30pm on Friday Hong Kong time.

Alaska Airlines did not disclose the cause of the outage.

The airline also addressed customer complaints on social media, responding to posts about booking glitches on its website and questions over whether its app was affected too. (Reuters)