Ryanair says it's "too early" to say whether flights from Belfast could be cut as part of the company's move away from UK airports in the wake of Brexit.
The low cost carrier made a return to Northern Ireland earlier this year, and now flies 11 routes from Belfast, with five daily flights to London's Gatwick.
In April, Ryanair said it could have 40 routes operating from Belfast International Airport and four million passengers in the next two to three years.
It now says it will "pivot" growth away from UK airports and instead focus on hubs in the European Union following the Brexit referendum result.
Asked whether flights to and from Belfast could be reduced, including the regular London Gatwick link, a spokeswoman said "it's too early to determine".
"Until some clarity emerges over the next two years about the UK's long-term political and economic relationships with the EU, we will be unable to predict what effect it will have on our business and regulatory environment, but we have contingency plans in place for all eventualities.
"In the meantime, we will pivot our growth away from UK airports and focus more on growing at our EU airports over the next two years. This winter we will cut capacity and frequency on many London Stansted routes (although no routes will close) where we are already significantly ahead of our multi-year traffic growth targets."
Speaking to the Belfast Telegraph earlier this year, Ryanair's chief marketing director Kenny Jacobs said the airline's growth in Belfast had been "unprecedented" across the company.
Ryanair says bookings for the initial seven routes have been strong, while the Gatwick route is also busy. It now flies to a range of destinations including Berlin, Tenerife, Alicante and Milan. It also added a further three new routes to Poland, including Gdansk, Wroclaw and Warsaw.
The company said there could be further implications if the UK is unable to negotiate access to the single market and the open skies regulatory framework currently in place across the EU.
The Irish carrier yesterday said that it could benefit if "our UK registered competitors are no longer permitted to operate intra-EU routes, or must divest their majority ownership of EU registered airlines".
The company made the remarks alongside first-quarter results, which saw net income rise 4% to €256m (£214m) and revenue rise 2% to €1.69bn (£1.4bn).
Ryanair said it was hit by market volatility arising from terrorist events and repeated air traffic control strikes in the period which caused almost 1,000 flight cancellations.
Launching Ryanair's return to Belfast in March, Michael O'Leary voiced strong opposition to the UK leaving the EU, claiming there was no upside to a Brexit. He said he was confident Ryanair would see a million passengers passing through Belfast International.
Ryanair used to operate from Belfast City, but pulled out in 2010.