French authorities said on Friday they seized a Ryanair plane, forcing 149 London-bound passengers off the aircraft, to get  the Irish low-cost airline to repay illegal public aid, the latest in a string of troubles for the carrier.

Claiming that Ryanair owed them 525,000 euros ($595,000) in subsidies wrongfully paid out to the airline, the authorities sent in a bailiff under police protection on Thursday to seize the plane on the tarmac of Bordeaux airport as it was readying to take off for London Stansted.

Just under 24 hours later, the no-frills airline relented and paid up, authorities said Friday, allowing it to reclaim its aircraft.

'Last resort'

“This measure was taken as a last resort by the French authorities after several reminders and attempts to recuperate the money failed,” the DGAC civil aviation body said of the seizure.

The EU Commission in 2014 ruled that subsidies Ryanair received from a regional authority a decade ago had to be repaid, but the airline had not complied despite repeated warnings, it said.

The move on the plane, a Boeing 737, on Thursday at Bordeaux's Merignac airport in southwestern France came after Ryanair failed to respond to a final warning delivered in May, prompting the order to seize the aircraft, DGAC told AFP.

“By this action, the government reaffirms its intention to guarantee the conditions of fair competition between airlines and between airports,” DGAC 
said.

'Regrettable'

It was “regrettable” that the passengers on board the plane had to wait five hours before being able to take off from the Bordeaux-Merignac airport in another Ryanair aircraft, the civil aviation body added.

Charente airport union leader Didier Villat told SudOuest newspaper: “To my knowledge it's the first time a Ryanair plane has been seized in this way.”

“Just because we manage a little airport in Charente it doesn't mean we are not going to defend ourselves,” he added.

A statement from France's aviation authority the DGAC read: “By this act the French state reaffirms its desire to guarantee the conditions of fair competition between airlines and its airports,” adding that the move to seize the plane was a “last resort” after several failed efforts to reclaim the debt.

The plane “will remain immobilised until the sum is paid”.

Passengers who were supposed to board the grounded flight were put on another plane that left five hours later. The DGAC called the disruption to passengers “regrettable”.

The Local has approached Ryanair for comment. 

Last month, EU anti-trust authorities opened an investigation into whether Ryanair benefited from measures at a German airport that give the Irish low-cost carrier an unfair leg-up over competitors.

And last week ministers from five European governments warned Ryanair that it could face legal trouble if it ignores national labour laws after a series of strikes across the continent.

The pan-European stoppages prompted the airline to cut its profit forecast, but it still expects to make profits after tax of 1.10-1.20 billion euros in its current financial year.

Ryanair is also fighting an order by Italian regulators to suspend a charge for carry-on bags.