An attempt by the Dublin Airport authority to seek changes to the way slots are allocated at the airport has been turned down by the aviation regulator, Mr Bill Prasifka.

The authority, formerly Aer Rianta, wanted the airport to become what is known as a "fully co-ordinated" airport. This would mean that in order to avoid congestion, airlines would have to accept a mandatory system of slot allocation.

The current system, described as "co-ordinated", allows the airlines to operate on a purely voluntary basis. This is popular with airlines because it allows them to retain operational flexibility.

Mr Prasifka commissioned a consultancy team, Alan Stratford and Associates, to look into the issue and has decided not to change the system, at least in the short term. The report did not identify any serious capacity problems at the airport which could not be resolved in the short term.

However, Mr Prasifka said yesterday that if capacity increased substantially within the next three years things might change. The daily responsibility for slot allocation is currently held by a private company called Airport Co-ordination Ltd. This company holds the contract which is awarded by the Office for Aviation Regulation.

Meanwhile, Knock International Airport yesterday said its passenger numbers increased by 55 per cent to 287,000 during the period January to September.

Commenting on the figures, Mr Liam Scollan, chief executive, said 2004 was so far a very positive period for the airport.

"We have just commenced a short October-November charter service to Cape Town. In the last quarter of this year we will operate skiing charters to Andorra with Panorama Holidays.

"Also, United Travel is offering one- and three-day excursions to Lapland in December to see Santa.

"EasyJet will start a London-Gatwick service in January, and in summer 2005 both Stein Travel and Falcon/JWT will operate charters to Faro," he said.