NEW YORK, July 21 (Reuters) - More than 1,200 flights

have been canceled within, into or out of the U.S. on Sunday,

led by cancellations in top carriers Delta Air Lines ( DAL ) and

United Airlines, according to data tracker

FlightAware.com, in the wake of Friday's global cyber outage.

Airlines are struggling to recover from the tech outage that

forced multiple carriers to ground flights on Friday.

United on Sunday said it had no further comment following an

update on Saturday. It said on Saturday that most of its

technology systems have been restored, but that it will continue

to see cancellations and delays this weekend. It also said it

had extended a travel waiver through Sunday for customers.

CNBC reported Sunday that Delta was offering its crews extra

pay to staff flights as it recovers from the outage.

A software update by global cybersecurity company

CrowdStrike ( CRWD ), one of the largest operators in the

industry, triggered the recent systems problems not just for

airlines but in other services as well, such as healthcare and

banking.