The number of British people flying into the State’s biggest airport is “falling like a stone” amid growing uncertainty about Brexit’s impact on air travel.

Kevin Toland, chief executive of DAA, the State company that runs Dublin and Cork airports, has told the European Parliament that growth in other business is concealing a decline in British travellers to the Republic.

Mr Toland said that Dublin Airport’s passenger numbers were up 6 per cent so far this year. “What that’s really disguising is the fact that inbound trips from the UK are down 7 per cent and falling like a stone,” he added.

“So our good performance, in outbound, as the Irish economy picks up, as North American, Middle Eastern and European business works well, is disguising the fact that there is already a Brexit-related decline.”

He explained that 42 per cent of tourists and 44 per cent of business travellers visiting the Republic come from Britain.

Mr Toland warned that, while March 2019, when the UK is scheduled to leave the bloc, seemed far away, airlines would begin planning for that time early next year, when uncertainty about what will happen was likely to persist.

He was addressing a meeting of the parliament’s transport committee, which questioned a number of aviation industry figures about the potential impact of the UK’s exit from the EU on air travel.

Brexit throws a question mark over the UK’s participation in an agreement that allows member states’ airlines to fly freely throughout EU airspace.

Ryanair chief executive Michael O’Leary predicted that, in a “hard Brexit, no deal” outcome, there would be no flights between the UK and Europe for a period after March 2019.

“We will be cancelling flights. We will be cancelling people’s holidays for summer of 2019,” he said.

Mr O’Leary called the situation as a mess. “Brexit will be one of the great economic suicides notes in history,” he warned.