Police and customs officials found more than 2.2 tonnes of cocaine valued at around 157 million euros ($165 million) after searching the Panamanian-registered "MV Matthew" vessel.

"This is the largest drug seizure in the history of the State," said Justin Kelly, a police spokesperson, adding that three crew members were arrested and taken into custody.

The 189-metre-long bulk carrier was intercepted Tuesday by Irish naval forces who fired warning shots before boarding and escorting the ship to Cork port where it is currently detained.

Irish justice minister Helen McEntee said in a statement that the drugs on board would have "no doubt been destined for Irish and European markets".

"It will represent a blow to the organised-crime gangs involved in drug distribution internationally," she said.

According to the Irish Times, police were tracking the vessel on suspicion it was carrying cocaine from South America and making deliveries of the drug to smaller vessels at sea.

After a fishing trawler ran aground on a sandbank off Ireland's southeastern coast Sunday, police rescued two men from the boat before arresting them on suspicion of organised-crime offences.

Kelly said such a large shipment would not have entered Ireland's waters without the involvement of an Irish gang.

There are a number of gangs in Ireland with "direct links to South America," he said.