Ryanair chief executive Michael O'Leary has confirmed his plans to make a return to Belfast with a "large base".
Addressing the annual Dublin Chamber of Commerce lunch yesterday, he also revealed fares would fall as much as 10% next year due to falling oil prices.
Mr O'Leary added: "Very shortly I hope we will be announcing a base in Belfast.
"We will be expanding into Belfast and making it another large base in Ireland and the UK."
The airline withdrew from Belfast City Airport in 2010 following a row over the runway's extension, but it is tipped for a return to Belfast International.
Speculation about the move has been growing since new take-off and landing slots became available at London's Gatwick Airport.
The British Airways owner, IAG, has been forced to give up the lucrative slots following its takeover of Aer Lingus, and Ryanair has been trying to acquire them, bidding against other airlines.
Industry sources have said there is a "strong likelihood" that Ryanair will secure at least some of the Aer Lingus slots and will run a Gatwick service from Belfast International, in competition with easyJet on the same route.
A Ryanair spokesman told the Belfast Telegraph last month: "As we have stated, should we secure workable Belfast-Gatwick slots, then we will launch a high frequency service, but we have had no confirmation to date."
Ryanair has made no secret of its desire to return. Chief marketing officer Kenny Jacobs said the airline was in "discussions with both airports with a view to operating flights to and from Belfast in the future". He added: "Ryanair is always interested in new routes. There is huge demand for Ryanair from customers in Northern Ireland who already travel with us from Dublin."
A spokesman for Belfast International Airport refused to comment last month on the speculation about Ryanair, but added: "We talk to a range of airlines on an ongoing and frequent basis."
Mr O'Leary told the Dublin Chamber that he expects average fares to fall from €47 (£34) to about €42 (£30) next year.
This is because the company is paying less for its fuel due to a reduction in oil prices. The cost of oil has plummeted over the past 12 months and sunk beneath $40 (£26) a barrel for the first time since the financial crisis this week.
Ryanair buys its fuel in advance, a policy called hedging.