Officers put checkpoints in place on Wednesday amid fears splinter groups were planning a return to violence.

But at a meeting of the North South Ministerial Council's summit today, Sinn Fein's Martin McGuinness described them as "no-hopers who want the Army back on the streets".

He arrived in the border town of Dundalk with First Minister Ian Paisley for the conference, which involved Irish Government and Assembly ministers, and Taoiseach Bertie Ahern.

Mr McGuinness said: "There are still people within our society who believe that violence is the way forward.

"Well my message to them is they who believe that are no-hopers.

"They are people who are going nowhere and they are people who are totally and absolutely detached from the reality of life on this island at this time."

He added that even though people still had the right to protest over his party's decision to power-share with the DUP, anyone who thought a return to violence was a way to break the Assembly was "living in cloud cuckoo land".

Although Mr McGuinness dismissed the dissidents as no-hopers, Mr Paisley warned the threat to security was very real.

This was echoed by Irish Premier Bertie Ahern.

Mr Paisley said: "I think it is serious and I think it has been confirmed by the police on the southern side as well.

"But, of course, we are not going to let that stand in our way.

"We are going forward and I am just saying to the people: you have a task to play. Play it with us and we'll get through."

The Dundalk summit is the second such meeting involving Irish Government and Stormont Executive ministers since the return of devolution last May.

Ministers announced they are now looking ahead at north-south cooperation in tourism, transport and the economy.