Consumers face having flight tickets that airlines won't be able to honour if bilateral aviation agreements aren't successfully negotiated by the time the UK leaves the EU, a leading airports body has warned.
Airports Council International (ACI) Europe has urged that the rules that will govern aviation activity between the UK and the EU be quickly resolved to provide clarity for passengers, airlines and airports.
The warning came as new figures from the UK's Civil Aviation Authority (CAA) show that the number of flyers between Ireland and the UK rose 10.5pc last year to just under 12.8 million.
The Dublin-Heathrow route remained the busiest out of Ireland, with 1.75 million passengers flying between the two airports last year, a 4pc increase on 2015.
Ireland is the EU member most exposed to the UK for air traffic, with 39pc of all air passengers travelling either to or from the UK, according to the airports body.
Olivier Jankovec, the director general of ACI Europe, said that the aviation industry will be left in the dark for months about what the status of the relationship between the UK and the EU will be once the UK leaves the trading bloc.
"Unless quickly resolved, this uncertainty will end up constraining route network development for airports, ultimately affecting air connectivity for their communities," Mr Jankovec said at the ACI Airport Economics and Finance Conference in London.
He said that airline route planning has a long lead time and requires legal certainty.
ACI Europe insisted that if exit terms aren't properly concluded within two years, then market access could fall back on more restrictive bilateral provisions between the UK and the EU, with potentially disruptive effects on air connectivity.
"Consumers could find themselves having purchased air tickets that airlines might not be able to honour in the absence of an appropriate legal basis for them to fly," claimed the organisation.
"The potential impact of this on air connectivity, consumers and the wider economy needs to be addressed by Brexit negotiators - on both sides," said Mr Jankovec.
ACI Europe added that 53pc of all passengers handled by UK airports are flying either to or from other EU member states.