The US administration has frozen the assets of four loyalist and one republican paramilitary group as part of its campaign against terrorism around the world.
The groups are the Ulster Defence Association/Ulster Freedom Fighters, the Loyalist Volunteer Force, the Orange Volunteers and the Red Hand Defenders as well as a republican splinter group, the Continuity IRA.
The move brings the US into line with the European Union which had singled out the five groups on its list of paramilitary organisations against which it intended to impose financial sanctions last Friday.
State Department officials designated the groups as suspected terrorist organisations but said it was too early to be sure whether any of them actually had financial assets in the US.
In October, the Ulster Unionist leader, Mr David Trimble, appealed to the US administration to crack down on the profits of such groups following the killing of investigative journalist Martin O'Hagan by loyalist paramilitaries.
According to a BBC report, the Secretary of State, Mr Colin Powell, decided on the list in consultation with the Treasury Secretary, Mr Paul O'Neill, and the Attorney General, Mr John Ashcroft.
A spokesman for the State Department, Mr Philip Reeker, said he welcomed the EU's decision to impose sanctions on the groups. A consistent fight against terrorism could only be waged with international co-operation in the fullest measure, he added.
The State Department also named the Spanish First of October Anti-Fascist Resistance Group as one of its targets for financial sanctions. The EU's list of proscribed organisations includes 13 groups and 29 individuals, most of them suspected members of the Basque separatist group, ETA, as well as some Saudi, Kuwaiti and Lebanese nationals.