Around 8.7 million customers across MAG's three airports – Manchester, Stansted and East Midlands – have been affected. The compromised data relates to customers who had used in-airport WiFi or made bookings for car parking, airport lounges or Fast Track security services.

Information obtained include email addresses, phone numbers, vehicle registrations and post codes, although MAG has confirmed none of the systems that were accessed hold customers' bank or payment details.

"We immediately contained the risk and have been working with specialist advisors and taking appropriate steps to protect our customers and systems," said MAG in a statement.

According to MAG, the incident has not resulted in any operational disruption, with airport operations "remaining unaffected" including customer parking services. All existing bookings also remain valid and customers do not need to take any action in relation to upcoming travel. 

However. as a precaution, MAG has temporarily suspended access to its online Manage My Booking service.

MAG said it has contacted customers whose data was affected by email and is urging them to remain alert to suspicious emails, text messages and phone calls.

Customers have been advised not to click or tap on links or open attachments in any "unexpected communications".

The Information Commissioner's Office (ICO) has confirmed it has received a breach report from MAG and is assessing the information provided.

A statement read: "We understand that these incidents can be concerning for the public. Anyone worried about their personal information can visit the ICO website for advice and support.

"We also advise checking regularly for updates from the organisation impacted and following their advice if they confirm that an individual's personal information has been compromised."