Suspicions were raised when the airport’s flight information screens went offline, with staff reportedly resorting to whiteboards and paper solutions.

Despite powering down various systems between Friday morning and Sunday morning, flight operations continued unaffected “with minimal disruption”.

The airport confirmed in a statement part of its administrative systems were subjected to a “speculative online criminal attempt on Friday (September 14)”.

A spokesperson for the airport said: “A number of processes, including the application providing data for flight information screens in the terminal, were taken offline purely as a precautionary measure while the problem was contained and to avoid any further impact.

“Established contingency plans were implemented to keep passengers informed about flight information. This included frequent announcements and additional staff in the terminal assisting passengers. Flight operations remained unaffected throughout.”

The airport on Monday confirmed its systems were back online, adding a full investigation was under way.

Dave Lees, Bristol airport chief executive, said:  “We are grateful to our passengers for their continued patience and understanding.

"With the cooperation and assistance of our staff, airlines and business partners we were able to implement contingency plans which ensured all flights operated with minimum disruption.”