Aer Lingus is launching nine new routes from three of its bases in Belfast, Dublin and Cork.
The routes will begin in time for next summer. The airline will begin services from Belfast to Milan in northern Italy, Munich in Germany and to Lanzarote.
Dublin customers will be able to fly to Catania in Sicily, Sofia in Bulgaria and Newcastle in England. From Cork, Aer Lingus will begin flights to the Canary Island of Lanzarote, Lisbon in Portugal, and Rennes in France. Seventeen of the airline's other routes will become more frequent from next summer as well.
From this November, Aer Lingus customers will be able to use American routes and networks under a new agreement with United Airlines. The Irish company and the American carrier have begun a code- sharing agreement, which makes it easier for Aer Lingus customers to travel throughout the US.
From April 2009, Aer Lingus will also place its code on United's domestic flights, which will give customers access to United's entire North American network.
The codeshare agreement will cover all six of Aer Lingus' US gateway airports, including New York (JFK), Boston, Orlando, Chicago-O'Hare, San Francisco and Washington DC.
Due to this agreement, Irish customers will have access to almost 200 additional destinations in the US through United's hubs in Chicago, San Francisco, and Washington.
US customers of United Airlines will also benefit from greater access to destinations in Ireland and to destinations in Britain and in Europe through Aer Lingus's extensive short-haul network.
Dermot Mannion, Aer Lingus chief executive, said this new agreement will change the way Irish passengers travel to the US.
"The relationship with United Airlines extends our offering to both our Irish and North American customer base, with seamless travel options and access to more than 200 destinations served by United Airlines in the US. We believe that this agreement will strengthen our position in the US market as we capitalise on the scale and the strength of the United Airlines network."
The United flight code is now available on all Aer Lingus transatlantic flights to and from Ireland, and on flights between Ireland and both London Heathrow and London Gatwick.