Senior Sinn Fein members were involved in sanctioning robberies including the Northern Bank raid, the Independent Monitoring Commission has said.
More than £26m was stolen from the Northern Bank
The commission's report said the party should bear its share of the blame for a series of robberies and that it should face financial sanctions.
The IMC backs the police assertion the IRA was behind the £26m raid in Belfast in December - a claim the IRA denies.
Sinn Fein said it rejected the report because the IMC was "not independent".
Republicans blocked some roads for a time in Belfast, Londonderry and Newry in protest at the report.
The IMC's findings, released on Thursday, are based on intelligence information.
The four-strong commission also blames the paramilitary group for robberies in Belfast and County Tyrone in which several people were abducted.
"In our view, Sinn Fein must bear its share of responsibility for the incidents," said the commission.
"Some of its senior members, who are also members of PIRA (Provisional IRA), were involved in sanctioning the series of robberies."
It added: "Although we note Sinn Fein has said it is opposed to criminality of any kind, it appears at times to have its own definition of what constitutes a crime."
Rejecting the commission's findings, Sinn Fein President Gerry Adams called on Irish prime minister Bertie Ahern to "put up or shut up".
Mr Adams challenged the taoiseach and the Irish authorities to arrest him over the bank raid.
"Previously they were saying the IRA was involved, and by dint of membership of the IRA leadership, that some members of Sinn Fein were involved. Now they are saying that Sinn Fein sanctioned this - that is untrue," he said.
"The person who first articulated this position was the taoiseach - he is the person who has to stand all of this up."
He added: "For me, he has brought all of this to a point where he has to back up his comments or he has to stand down from them."
In response, the Irish government said the taoiseach had no such power, and dismissed Sinn Fein's challenge as "a publicity stunt".
The commission said it would have recommended Sinn Fein's exclusion from office if the assembly was still sitting.
The IMC's findings are based on intelligence information
In the absence of devolution, Secretary of State Paul Murphy should consider imposing financial penalties, it said.
The IMC said the IRA carried out a robbery at the Makro store in Dunmurry in May last year, the abduction of people and robbery from an Iceland store in Strabane last September and a £2m cigarette robbery and abduction of people in Belfast last October.
"We believe that the Northern Bank robbery and abductions, and the other robberies and abductions... were carried out with the prior knowledge and authorisation of the leadership of PIRA," said the commission.
PSNI Chief Constable Hugh Orde's belief the IRA was behind the raid was also backed by the Garda Siochana in the Republic of Ireland.
However, the IRA denies the claims and, last week, it withdrew its offer of complete decommissioning.
Mr Murphy, speaking after the report's publication, said: "I shall now consider carefully the commission's recommendations. I plan to make a further statement to the House in the week of 21 February."
An Irish government spokesman said the IMC's conclusions concurred with the intelligence available to both governments in relation to the Northern Bank robbery and other incidents in Northern Ireland.
DUP deputy leader Peter Robinson called for the political process to continue without Sinn Fein.
"Society should not be held to ransom by gunmen and gangsters," he said.
Ulster Unionist leader David Trimble said: "I call on the government to publicly state that if the assembly was sitting and if the assembly failed to pass a motion of exclusion, they would, if necessary use the new statutory powers that they have... to exclude Sinn Fein."
SDLP leader Mark Durkan said: "The SDLP believes the best way forward is not through silly sanctions. It is by showing Sinn Fein - and the DUP - that they don't have a veto on change. We need a process of equals instead."
Conservative Northern Ireland spokesman David Lidington said it was an "affront to democracy" that Sinn Fein could access Commons facilities and receive allowances "at the same time as they are involved with an armed and active criminal gang".