Ryanair is one of several low-cost operators exploring taking over new slots that have become vacant at Belfast International Airport following the departure of Bmi British Midland.
A Ryanair spokeswoman has confirmed the airline has held discussions with Belfast International about developing new services.
Bmi British Midland was one of the largest airline operators at Belfast International, carrying up to 700,000 customers each year.
Its surprise decision to switch all its services from Belfast International to Belfast City after 20 years has created many slots which the owners of the international airport, TBI, are under pressure to replace.
Ryanair operates a daily service between the City of Derry Airport and Stansted in London.
It does not have a presence at either Belfast International, where EasyJet operates from, or Belfast City Airport, which has no plans to attract low cost operators.
Ryanair claims to carry around 10,000 passengers a month between Derry and London, Mr Michael O'Leary, the airline's chief executive, has said it is the second fastest growing airport in Ireland for Ryanair.
Last year, the airline carried 125,000 passengers from Northern Ireland and it expects this to grow in the current year to 160,000.
Sources close to Belfast International Airport said yesterday that no deal had been done with Ryanair but industry sources said the group would have noted the success of EasyJet's operation at the airport.
Next to Bmi British Midland, EasyJet is a major carrier from Northern Ireland. Its passenger figures are expected to grow to one million people this year.
It operates 19 flights daily between Northern Ireland, the UK and Amsterdam. TBI, currently the subject of a hostile bid from French construction group Vinci, is confident it will replace its former Bmi British Midland business in Northern Ireland.
But the airports' group has warned that the loss of Bmi is likely to wipe £2 million sterling (€3.2 million) off profits this year and up to £6 million next year.
TBI owns and operates nine airports throughout the UK, Europe, the US and South America, Belfast is one OF the group's key profits drivers.
Vinci has bid 90p sterling a share for TBI valuing the group at £516 million, an offer rejected by its directors as "opportunistic".
The offer values TBI at a 50.6 per cent premium to the group's closing price on August 13th the last business day before the French group's expression of interest.
However, city analysts believe a fair value for TBI is around 100p per share, TBI shares closed at 98.75p a share on the London Stock Exchange last night well above Vinci's initial offer.
The French group is expected to file a formal offer document for TBI by the end of this week but the airport operator has confirmed that at least two potential rival suitors have emerged.
The Australian investment bank, Macquarie, and the Spanish construction group, Grupo Ferrovial, are widely tipped as the most likely candidates.
Both Macquire and Group Ferrovial were involved in a consortium that tried to buy Bristol Airport in the UK for estimated £200 million sterling last year.
Neither organisation has commented and the UK group has declined to disclose the identity of its two potential suitors.
Businessman Mr Dermot Desmond who owns a 3.3 per cent stake in TBI and also has a stake in London City Airport has also refused to comment on whether he might be involved in a consortium which may table a bid for the UK airports' group.
