Delta Air Lines Inc said it was canceling more than 500 flights worldwide on Tuesday as the carrier worked to restore operations after a power outage hit its computer systems on Monday.

The company, which has not yet detailed the financial impact of the outage, said on its website that as of 12:30 p.m. EDT (1630 GMT), it had canceled about 530 flights, while about 1,600 had departed. Earlier in the day, it estimated the cancellations at nearly 250.

The company said it would extend through Tuesday a waiver of fees normally collected when travelers change flights.