The airport owned by well known businessman Jim Mansfield has been facilitating foreign flights despite having no legal permission to do so, The Irish Timeshas learned.
Mr Mansfield's spokesman said all affected flights had now been directed to use Dublin Airport to clear immigration before flying to Weston Airport.
An application has now been made to secure port of entry status for Weston. A spokeswoman for Minister for Justice said this was being considered.
Between 600 and 800 flights have used the airport in the last three years that should not have. The matter is likely to raise serious questions about security at small Irish airports.
The planes have been entering the State through Weston Airport, Leixlip, Co Kildare, without the consent of the Minister for Justice Michael McDowell, who designates port of entry status on airports.
In response to queries last night Supt Kevin Donohoe of the Garda Press Office said because Weston does not have port of entry status, no Garda immigration checks are carried out there.
He said an exception was made in the period surrounding the Ryder Cup, "during which special arrangements were put in place within the law".
Security sources said this was the only time that Weston was entitled to facilitate planes or passengers from outside the common travel area between Ireland and the UK.
News of the breaches have emerged following the discovery of cocaine and heroin valued at €6 million in Belgium last September as it was being taken for loading on to a private jet owned by Mr Mansfield for its transportation to Ireland via Weston.
Mr Mansfield said he was unaware his plane had even been taken out of the country.
He told The Irish Timeshe was informed by the Garda in late January he had no permission to facilitate aircraft at Weston whose journeys originated from outside the common travel area. Mr Mansfield said before gardaí contacted him he was unaware he should not be facilitating some planes and passengers. He said he was never contacted.