Police forces on both sides of the border have said the threat from dissident republican groups remains severe in spite of a recent reduction in terrorist attacks.
Garda Commissioner Martin Callinan and PSNI Chief Constable Matt Baggott were speaking after a cross-border police conference on organised crime.
The two men said said dissident groups were involved in all sorts of criminal activity north and south of the border and warned against complacency.
They said groups such as the Real IRA are now engaging in violent extremism as part of a claim that they too are taking on the forces of global capitalism but that this message needs to be confronted.
They said bombing banks has nothing to do with the problems of the working class.
Meanwhile, Minister for Justice Alan Shatter said gardaí may not get back from the Government all the money they spent earlier this year on security for the visits of Britain's Queen Elizabeth and Barack Obama, which cost €36m.
The minister also said that an announcement would be made in the next two to three weeks in relation to which garda stations would be closing.