Gardaí learned from a major emergency training exercise to intercept a ship in the Irish Sea, a senior commander said.

It simulated a scenario in which a vessel was detected interacting suspiciously with an unregistered fishing boat.

The scene developed into a mock hostage-taking at a warehouse on the dock at Drogheda Port.

Chief superintendent Sean Ward said: “I am happy with the way it went today, I think we learned a lot from it.

“I have no doubt there were deficiencies at some stage along the line and they will be identified.”

The emergency response unit was tasked with boarding the vessel with the assistance of the Garda Water Unit.

Later a suspect acting suspiciously on the dock watching the activity at sea took a man and woman hostage and sought refuge in a port warehouse.

He had a firearm and brought two hostages into the warehouse with him.

Gardaí “negotiated” with him over a telephone which they threw into the building.

Ultimately the two hostages were freed. The gunman was injured when police using arms, shields and smoke bombs raided the building using smoke bombs.

Chief Supt Ward added: “It is a learning process so that people know that if something like this happens, and again it gave an opportunity for everyone involved, both from the Garda Síochána, the Drogheda Port Company and the national units as well to get to know each other and to link together, so that if an emergency like this happens you know who you are dealing with and you can work better together.

“The scenario is only the way you do the actual exercise. It could be any type of scenario.”

The operation, which began at around 9.30am and lasted several hours, involved members of the Garda command, air and sea units, emergency response and regional support.