Delta Air Lines officials on Tuesday said they will refund fares and offer $200 in travel vouchers to passengers who were left stranded on Monday after more than 700 flights had to be cancelled because of a power outage at the airlines' Atlanta headquarters. The offer is also valid for people whose flights were delayed for at least three hours.

Although the power outage issue has been resolved, the airline on Tuesday grappled with accommodating scores of passengers. Delta Air Lines officials said they may have to cancel 100 more flights on Tuesday and around 200 may be delayed, reported CNN. Delta is the world's second largest airline with more than 5,000 flights daily to six continents.

Delta spokesperson Trebor Banstetter told AP that after the power outage, some important systems and network did not switch to backup systems and added that an investigation was on to find out the cause of the outage. He, however, ruled out the possibility of hacking.

On Monday, Delta cancelled more than 740 flights while around 2,600 flights were delayed worldwide. In Richmond, Virginia, Delta agents had to issue hand-written boarding passes while in Tokyo, a dot-matrix printer was resurrected to keep track of passengers on a flight to Shanghai. However, the outage did not affect those flights that had already taken off.