Gardai demanded handwriting samples from 223 passengers and nine crew members during a major security operation at Dublin Airport after a note was found on an Aer Lingus plane warning of a bomb on board.
The operation began at about 9.30am on Saturday when the transatlantic flight travelling from New York to Dublin landed at Dublin Airport.
One of the crew members on the flight had reported finding a paper towel in the toilet of the plane with a written warning that there was a bomb on board.
The plane landed and taxied to a secure location some distance away from the airport terminal and was secured by armed gardai.
Passengers disembarked and interviews were conducted in the terminal building. Passengers were asked to supply samples of handwriting.
A full-scale search of the aircraft got under way using sniffer dogs from the garda dog unit. However, nothing was found.
In a statement the national carrier said: "Aer Lingus flight EI 108 from New York to Dublin, carrying 223 passengers and 9 crew, arrived today at Dublin Airport at 10.10 am.
"Aer Lingus confirm that following a security alert on board the flight, the authorities were informed by the flight crew.
"As a precaution gardai met the flight on arrival at Dublin and spoke to the passengers."