BELFAST (Reuters) - Northern Irish militants hoped a bomb they planted on a haulage lorry last week would take a ferry across the Irish Sea and explode in Britain at the time it left the European Union, police said on Thursday.

Police first received a telephoned warning via a media outlet on Jan. 31 that there was a bomb in a lorry in Belfast docks which was due to go by ferry to Scotland from British-run Northern Ireland, but they could not find the vehicle.

The ferry sailed and arrived safely on the day Britain left the EU - an exit that proved highly divisive in Northern Ireland.

On Monday, police received a second phone call, this time providing the name of the haulage company the lorry belonged to, which led them to the vehicle which had never left Northern Ireland.

“They did intend, we believe, and they said, that the device would explode at around the time the UK left the EU,” Assistant chief Constable George Clarke told a news conference on Thursday.

The police said the bomb was planted by pro-Irish militants known as dissidents who oppose the 1998 Good Friday peace accord and have continued a low level campaign of violence.

The explosive device was found attached to a heavy goods vehicle in the Silverwood Industrial Estate in the town of Lurgan in County Armagh, Northern Ireland.

The police said the device put the driver of the vehicle, road users, and the wider public at serious risk of injury and possible death.

(This story corrects headline to show bomb bound for British mainland, not UK)