The Irish Congress of Trade Unions said it was a matter of “very serious concern” that the Government had failed to achieve any guarantees on possible job losses and outsourcing in Aer Lingus, despite some progress on issues such as connectivity and slot retention.

Congress general secretary Patricia King said: “While there has been some obvious progress, there was also a very clear failure to achieve guarantees that there would be no compulsory redundancies or outsourcing, following any IAG takeover.”

She added: “Our fears about the loss of existing jobs in the event of an IAG takeover have not been assuaged.”

Tourism Ireland said the decision would boost tourism to Ireland from North America. “Today’s announcement that Aer Lingus, within the IAG family, plans to add four transatlantic flights, increase its fleet by eight new aircraft and carry up to 2.4 million additional passengers by 2020 represents a huge boost for the tourism sector,” said the chief executive of Tourism Ireland, Niall Gibbons.

The Irish Hotels Federation said it welcomed the additional guarantees secured by the Government. Its president, Stephen McNally, said the commitment in relation to Aer Lingus’ s Heathrow slots was a significant development that would provide greater certainty for routes into Dublin, Cork and Shannon airports.

Shannon Airport also welcomed the Government’s decision. The chairman of Shannon Group plc, Rose Hynes, said: “It’s good news; it’s a positive opportunity for Ireland, will safeguard the Shannon-Heathrow connectivity for seven years and it opens the door to further growth at Shannon.”