Northern Ireland’s Junior Minister will seek a meeting with the Irish Government to retain a vital flight route after it emerged Belfast could lose its Heathrow slot if Ryanair’s bid to buy rival airline Aer Lingus is successful.

DUP MP Jeffrey Donaldson told the Belfast Telegraph that it would be detrimental for the local economy if Aldergrove Airport lost its Heathrow slot be

cause the province would become less attractive to investors who look for strong airport links to major hubs.

Yesterday speculation was mounting that Ryanair was planning to ditch the Belfast to Heathrow flights as part of its second bold bid to buy the airline from the Irish government.

Part of the plan is a promise to reinstate the Shannon-Heathrow route Aer Lingus closed last year in favour of flights to Heathrow from Belfast International Airport.

Ryanair said it proposed to “correct the deficiencies in Aer Lingus’ existing Articles, which allowed Aer Lingus to close the Shannon-Heathrow route and replace it with a Belfast-Heathrow route, despite the Government’s objection”.

“This guarantee will ensure that Heathrow’s connectivity to Dublin, Cork and Shannon can be protected by the current and future Irish Ministers for Transport,” the airline said.

However when contacted by the Belfast Telegraph last night, a spokesman for Ryanair declined to comment beyond the statement.

Earlier this year Aer Lingus cut its flights from Shannon Airport to Heathrow in favour of flights from Belfast.

The controversial move was welcomed in Northern Ireland, but however caused major upset in the Republic.

Last night Mr Donaldson said he would be talking to the Irish Government over Ryanair’s bold plan and “encourage them” not to withdraw the services.

“Certainly having worked hard to attract Aer Lingus to Belfast we would certainly not want to give those slots away again and we will be talking to the Irish Government — who were supportive of the Aer Lingus move in the first place — we would encourage them not to withdraw the slots,” Mr Donaldson added.

“Aer Lingus have done very well with those slots, they provide a vital link between Belfast International Airport and London.

“I think it would be very bad for the future of air service in Belfast if they were lost.

The slots from Belfast are vital because they provide a connection into the huge range of international flights out of Heathrow and therefore give Belfast connections to many parts of the world. If we lose the Heathrow slots that would be a major setback in terms of seeking to attract investment into Northern Ireland because many investors are looking for strong links to airports from places to Heathrow.”

A spokesman for Belfast International Airport said: “This is standard mischief making from Ryanair. The comments made are a bit rich coming from an airline that is threatening to take out a significant number of services from Shannon itself. This situation is entirely hypothetical anyway.”

Aer Lingus has so far declined all approaches and advised shareholders to reject Ryanair’s offer.

Ryanair has offered to buy Aer Lingus for €747.5m (£618m) — around half the sum that it tabled in a failed bid two years ago.

Boss of Ryanair Michael O’Leary yesterday set out a five point plan to protect former state airline Aer Lingus’ international standing and make the deal more appealing to the Irish government.

After meeting Irish Transport Minister Noel Dempsey, who controls a 25% Government stake, Mr O’Leary published details of the buy up plan.

The company’s commitments include:

• A promise to honour union agreements
• Plans to reinstate the closed Shannon-Heathrow route
• Handing control of the valuable Heathrow landing slots to the Irish Government
• A €200m (£73m) package to keep down costs of seats.

In a statement to the Stock Exchange, Ryanair said it was a substantial deal offering a unique merger.

The company said it would give consumers, the Irish government and the European Commission the confidence to accept the deal.