United Airlines and US Airways said Sunday they were resuming normal operations after computer outages that had delayed flights over the weekend.

Charles Hobart, a spokesman for Chicago-based United, said that hackers were not involved in a five-hour computer outage that virtually shut down United Airlines Friday night and early Saturday. United Air is part of United Continental Holdings Inc.

Hobart said that United was forced to cancel 16 flights on Friday and approximately 25 on Saturday because of the computer outage that also delayed about 100 flights worldwide.

By Sunday afternoon, he said that United did not expect additional delays because of the computer outage. "We continue to accommodate the affected customers and are returning to normal operations," Hobart said.

In the case of US Airways Group Inc., officials of that airline said that flights at the airline's Charlotte, N.C., hub were back to normal Sunday afternoon after a computer outage that began at 7:50 a.m. Sunday. The US Airways computer problems were not resolved for about 3.5 hours. Officials of the Tempe, Ariz., air carrier said their problems did not cause any flights to be canceled.

The computer troubles at United had stranded thousands of passengers and caused long lines of passengers to form at check-in counters at Chicago's O'Hare International and Denver International, two of United's largest hubs.