July 21 (Reuters) - U.S. Transportation Secretary Pete

Buttigieg spoke on Sunday with the CEO of Delta Air Lines ( DAL ),

following the carrier's cancellation of thousands of flights

since Friday due to a widespread IT-systems outage and as it

continued to try to restore operations, a department official

told Reuters.

Delta CEO Ed Bastian told customers on Sunday that the

carrier had canceled 3,500 flights through Saturday. Flightaware

said Delta on Sunday had canceled another 899 flights -- or 24%

of its schedule. Buttigieg during the call reminded Bastian of

the airline's responsibilities to customers and the department's

enforcement role, the official added.