Aer Lingus is expanding its fleet

The deal, which represents the airline's biggest ever spending spree, also includes options on a further 10 planes.

The Irish flag carrier took advantage of a slump in the aircraft industry to strike a bargain on the Airbus A320s.

It is attempting to reposition itself as a low-cost carrier, after a brush with bankruptcy in 2001.

New routes

The move to a single type of aircraft on its European fleet will bring cost savings and increased flexibility, Aer Lingus Chief Executive Willie Walsh said.

He said the airline planned to add 15 new routes by the middle of 2005.

"It is an excellent financial deal achieved at precisely the right time in the industry cycle," said Mr Walsh.

"More importantly, it reinforces (our) transformation into a low fares airline that offers a way better service."

'Good deal'

Aer Lingus has axed 2,000 jobs, a third of its workforce, in a bid to compete better with lower-cost rivals such as Irish no-frills carrier Ryanair.

Aer Lingus also talked to Boeing before reaching a deal to buy the Airbus A320s.

It will bring Aer Lingus's short-haul fleet to a total of 27 Airbus aircraft, including six existing A-321s and four A-320s.

While refusing to disclose financial terms, Corporate Affairs Director Dan Loughrey told Reuters: "It was an offer we couldn't refuse, an extraordinarily good deal."