British Airways has reported a problem with its computer systems at multiple airports on Monday night. The delay is said to be relating to BAs check-in system, making passengers experience long boarding lines and flight delays.

While some reports suggest that the system outage was across airports in the US, a few other reports citing passengers said the problem was being experienced worldwide. A statement by the Metro Washington Airport Authority also described the problem as a worldwide system outage.

Nevertheless, images on social media showed crowds gathered around BA counters from airports across Mexico City, San Francisco, Atlanta and Seattle. However, the number of flights that have been affected has not yet been reported.

A BA statement, cited by CNN, read: Our IT teams are working as hard as they can to quickly fix a problem with our check-in system. Were sorry for the delays some customers are experiencing as they check-in for their flights.

The British airline in a letter to customers at the San Francisco airport, stated that it was using a manual fallback process. The letter, as cited by NBC news, said We have been in contact with the relevant departments who are doing all they can to rectify the problem as soon as possible...However we are unable to ascertain a time when we might expect the systems to be functional again.

This is not the first time BAs computer systems have gone down in the US. On 29 May, the carrier witnessed a computer system outage at the John F Kennedy International Airport. This had then caused a lot of travel delays to hundreds of its passengers.

Apart from BA, other airlines too have seen similar outages. As recently as last month, Delta Air Lines, saw a similar outage. This had then caused about 2,000 flight cancellations. About three weeks earlier, Southwest Airlines had seen a system failure that had led to the cancellation of more than 1,000 flights.