British Airways (BA) on Friday said personal and financial data of its nearly 380,000 customers who booked online on its website and mobile app has been compromised.

Urging the customers to immediately contact their banks after their credit cards details were compromised, the airways said it was investigating the theft that happened between August 21 and September 5.

"We are investigating, as a matter of urgency, the theft of customer data from our website and our mobile app. The stolen data did not include travel or passport details," BA said in a statement.

"From 22:58 BST August 21 2018 until 21:45 BST September 5 2018 inclusive, the personal and financial details of customers making bookings on our website and app were compromised.

"The breach has been resolved and our website is working normally. We have notified the police and relevant authorities," the statement added.

The airways said if you believe you have been affected, please contact your bank or credit card provider and follow their recommended advice.

"We are deeply sorry for the disruption that this criminal activity has caused. We take the protection of our customers' data very seriously," BA said, adding the airways will be contacting affected customers directly to advise them of what has happened.

"Every customer affected will be fully reimbursed and we will pay for a credit checking service," said BA, urging the customers to change their passwords for log into its website and the mobile app.

This is not the first time the airways has been affected.

In July, nearly 7,000 passengers had their flights to or from Heathrow cancelled after a failure of an IT system provided to BA by Amadeus, a Spanish IT provider for global travel industry.

In May last year, a "power outage" triggered a collapse in the airline's information systems.