Ryanair's chief executive Michael O'Leary said Wednesday in Lisbon he did not agree with the decision because if there was a disruption in fuel supply, it would have to be a special circumstance and the airlines can not be liable.

Despite this, Ryanair will ask Galp for compensation because Galp admitted "it was not our fault," O'Leary said.

The Portuguese Civil Aviation Authority (ANAC) has said it was Ryanair's fault, he said, and therfore the company will try to be compensated by Galp.

Asked by Lusa, O'Leary said the issue involved a "small amount."

According to O'Leary the airline has had complaints from 400 to 500 passengers and that the amount is therfore not high, but he holds that it should be paid by Galp.

Two weeks ago, ANAC announced that airlines will have to compensate passengers for disruptions caused by a fuel shortage at Lisbon airport in May 2017.

Last week, TAP also announced that it would pay compensation to passengers as determined by the regulator and demand compensation from Galp.

The fuel system failure that occurred on 10 May at Humberto Delgado Airport in Lisbon affected 41,681 people, led to the cancellation of 98 flights, 363 took off late and 12 had to be diverted to other airports.