Two American men aged in their 80s have gone on trial accused of criminal damage and trespass at Shannon Airport on St Patrick's Day three years ago, leading to the closure of a runway.

Ken Mayers, 85, and 80-year-old Tarak Kauff, both with addresses in the US, are accused of damaging a perimeter fence before allegedly trespassing on the lands of the Co Clare airport, Dublin Circuit Criminal Court heard.

The pair, who were wearing high-vis vests bearing the words 'Veterans for Peace', walked on to a taxiway at the airport, causing airport personnel to close the runway for a period of time, Tony McGillicuddy BL, prosecuting, told the jury.

A plane which was due to land at the airport was unable to do so for the course of the warning, the court heard.

Mr Mayers and Mr Kauff have each pleaded not guilty to three counts in relation to the alleged incident.

Mr Mayers, of Monte Alte Road, Santa Fe, New Mexico, pleaded not guilty to criminal damage to a perimeter fence, with a value of €590, at the airport on 17 March 2019.

He also pleaded not guilty to trespassing on the curtilage of a building with the intent to commit an offence or unlawfully damage property.

He further pleaded not guilty to interfering with the operation, safety or management of an airport, namely by entering a runway area and causing it to close.

Mr Kauff, with an address at Arnold Drive, Woodstock, New York, pleaded not guilty to the same charges.

Opening the case, Mr McGillicuddy told the jury it would hear evidence that the two men broke through the perimeter fence between 10am and 10.20am on the day in question, with gloves and bolt cutters later found inside the grounds.

The court heard airport personnel were alerted to the incident and shortly afterwards, staff members saw two men in high-vis jackets on a taxiway in the airport. One of them was carrying an Irish flag.

The jury was told that the men were not aggressive or "awkward in any way" when approached by airport personnel.

They were wearing high-vis jackets with 'Veterans for Peace' written on them and they were engaged in a protest of some kind, Mr McGillicuddy said. "Anti-war activities of some nature," he said.

The men were arrested and taken to the local garda station for questioning.

"The runway had been forced to close because of their presence on the runway and that had a knock-on effect on the management of the airport," Mr McGillicuddy said.

He said it was the prosecution case that both of the accused men were involved in the criminal damage of the fence and that both men were involved in the unlawful interference with the operation and management of the airport.

He said it was the prosecution case that both men trespassed on the land of the airport with the intent or giving rise to the reasonable inference that they intended to commit an offence or unlawfully interfere with property in the airport.

Michael Hourigan BL, defending Mr Mayers, said his client "has admitted he was involved in making an opening in the fence at Shannon Airport".

He said his client also admits that he entered the curtilage, or lands, of the airport on the day in question.

He said his client was treated respectfully and courteously by airport staff and gardaí.

Carol Doherty BL, defending Mr Kauff, said her client made the same admissions as Mr Mayers.

The trial continues before Judge Patricia Ryan and a jury.