Airlines cancelled more than 100 flights Wednesday due to a four-hour strike by Irish air traffic controllers affecting Ireland's three main airports, the carriers said.

The Irish Aviation Authority (IAA) said "significant numbers of flights will be disrupted" and warned the industrial action by the controllers is "likely to escalate".

Aer Lingus said it had cancelled 64 flights affecting some 7,000 passengers, while budget carrier Ryanair cancelled 48 flights affecting over 6,000 passengers.

The action is unlikely to have a major impact on international flights through Irish airspace, which will probably be re-routed around the country, said an IAA spokeswoman.

Labour union IMPACT said the action at Dublin, Shannon and Cork airports follows the suspension of 15 controllers for refusing to engage in "disputed new work practices". It expects further suspensions by the IAA.

IMPACT official Michael Landers said the "core issues" in the dispute have been referred to the country's Labour Court and staff should not be suspended while the "process is ongoing".

The IAA called for a return to normal working and urged the union to suspend a six percent pay claim and pay a pension contribution "like everyone else in the public service".

It said the controllers are among the best paid public servants in recession-hit Ireland.

"On average, they cost the Irish Aviation Authority 160,000 euro (228,000 dollars) each. Earnings for the top 10 percent of controllers in the country last year ranged from 170,000 euros to 230,000 euros,"

The IAA said increased costs would have to be passed on and with the aviation industry "on its knees" airlines cannot afford to pay any increases in the current economic climate.