The Irish Aviation Authority has banned drones from flying over a site in Dublin where gardaí are carrying out a search as part of the investigation into the disappearance of Trevor Deely almost 17 years ago.
The Department of Justice made a request to the Minister for Transport asking him to impose flight restrictions for security reasons.
The request was acceded to and the ban will remain in place until the end of the month.
The flight restriction notice issued by the IAA applies to all unofficial aircraft including model planes and drones.
There are exceptions for emergency air ambulances and search and rescue aircraft.
Today is day six of the search of the three-acre site in Chapelizod.
The area has been divided into five zones and searches have been completed in two zones so far.
Mr Deely was last seen walking home after a Christmas party in the early hours of 8 December 2000.
Gardaí are investigating if he was killed by a known criminal whom he may have met by chance in the Baggot Street area.
Detectives are hoping the search, the most significant since the 22-year-old's disappearance, will lead to a breakthrough in the investigation.