Ryanair could potentially be on the hook for millions of pounds in compensation after a British court on Friday confirmed that passengers have up to six years to seek payouts for flight delays.   

A court in the northern city of Manchester ruled against the Irish low-cost carrier, which had told passengers in the fine print of its terms and conditions that they have a maximum of two years to lodge a demand.

Ryanair announced it will fight the decision that could clear the way for millions of passengers to seek recourse against the airline.

"We believe a six-year time limit for submitting such claims is both unnecessary and unreasonable, we have instructed our lawyers to immediately appeal this ruling," the company said in a statement.

The carrier argued that passengers who had accepted the company's terms and conditions with a two-year limit had given up their rights to seek compensation.

However, the court ruled that European Union regulations -- which lay out a six-year window -- are valid.   

Travellers are entitled to up to 600 euros each if their flight is three or more hours late, though some circumstances are exempted such as bad weather or security issues.  

According to some estimates the judgement could leave Ryanair liable for £610 million (856 million euros) in compensation, a figure the company called "absurd".

"Ryanair estimates that even if its appeal in this matter is ultimately unsuccessful, its potential liability will not be material," the airline said, estimating it at less than five million euros.

This case stems from complaints filed by six passengers on a March 2008 flight between the Spanish city of Reus and London which arrived nearly 10 hours late. The travellers filed their claims about five years and eight months after the trip.