DUBLIN (Reuters) - Pilots employed directly by Ryanair RYA.I in Dublin, its second largest base, have voted overwhelmingly in favor of taking industrial action in a growing dispute over the airline's collective bargaining system, the IMPACT trade union said on Monday.

Ryanair headquarters building is seen in Dublin, Ireland September 21, 2017. REUTERS/Clodagh Kilcoyne

The Irish airline, Europe’s largest by passenger numbers, is trying to recover from a damaging wave of flight cancellations caused by crew rostering problems, while pilots at fewer than a third of its 87 bases have accepted an offer to increase pay.

Several unions across Europe have been preparing for industrial action in a demand for better conditions at Ryanair with its pilots in Italy due to stage the company’s first ever strike by pilots later this week.

The Dublin ballot covered direct employees only, rather than the majority of pilots which the airline hires through agencies. Of the 84 ballots issued, 79 voted in favor of industrial action, with three against and one not returned.

Directly employed pilots are generally at the rank of captain so any strike action would likely cause disruption for passengers at the airline’s home base.

An IMPACT committee that Ireland’s IALPA pilots union operates under will meet on Tuesday to decide on the next steps, a spokesman for the union said.

Ryanair, which does not recognize trade unions, said in a statement that it has not received notification of any industrial action by its Dublin pilots and that it suspected the ballot was “more PR activity” by IALPA.

It said that it instead expected the Dublin pilots to follow colleagues at other Irish bases in Cork, Shannon and Belfast in signing up for a 20 percent pay increase.

“However, if Ryanair’s Dublin pilots are misled ... into industrial action, then they will lose their favorable rosters and remuneration benefits that are specifically linked by agreement to dealing directly with Ryanair,” the airline said.

Ryanair told its Dublin pilots last week it would freeze promotions, cut cash allowances and possibly move pilots to alternative bases if they voted in favor of industrial action.

Pilots have mobilized in the wake of the announcement of 20,000 flight cancellations by the Irish carrier, which it blamed on a lack of standby pilots due to a failure in its rostering following a rule change by Irish regulators.

Ryanair routinely dismisses “competitor pilot unions” who it says claim to represent more Ryanair pilots than they do. But several unions in recent weeks have formed company councils and named serving Ryanair pilots as members.