Anti-terrorist detectives in Dublin uncovered a huge bomb that was primed and ready to be detonated on Saturday night, leading to speculation that the bombers’ intended target was stage 3 of the Giro d’Italia, which arrived in Dublin on Sunday.

"This was a deadly, full-size bomb which had been wired up and ready for imminent use. If it had gone off it would have caused total devastation," a source told the Irish Independent.

The bomb was concealed in a milk churn in a car in the car park of the Finnstown Country House hotel in Lucan, Co Dublin. It contained 50lb of explosives made from fertiliser and had a timer attached.

The device was found after a 999 call to gardai at about 8.40pm on Saturday night.

Dissident republicans are suspected of transporting the bomb from Belfast to Dublin recently. It is believed the device was going to be moved from the Lucan car park to its intended target.

Although a man with links to the Real IRA has been arrested, it has not been confirmed that the Dublin finish of stage 3 of the Giro d’Italia was the target. But security sources believe that the bombers may have planned to stage a city centre atrocity to attract worldwide attention.

With hundreds of thousands of fans lining the streets of Dublin for the Giro and a worldwide audience estimated at up to 125 million, an attack on the race would certainly have fulfilled that aim.

According to security sources, the device, made safe by an Army Bomb Squad, was fitted with a Timer Power Unit, a hallmark of all major IRA bombs. Also known as a "safe to arm" switch, the TPU can be set to detonate at a given time, which can range from a few hours to several days or even months after it is set.