The group of IRA dissidents claiming to be the "true IRA" last night issued a statement saying that the organisation's ceasefire was over and military in attacks would resume.
It denounced the "old leadership", claiming it had betrayed republicanism in the fashion of "Collins and de Valera".
Its statement is likely to be strongly challenged by the mainstream republican movement which insists that it is the IRA and that its ceasefire remains intact.
The group claiming to be the new IRA is led by dissidents, including the quarter-master general, who resigned from the mainstream IRA seven months ago in protest at the peace process. It is much smaller in number than the mainstream IRA.
It is understood it has made its announcement because of reports than an IRA convention has given the go-ahead to Sinn Fein to accept the Belfast Agreement and enter a new assembly at Stormont.
The dissidents claim this decision is a breach of the IRA's constitution.
In a lengthy statement, accompanied by a recognised codeword, a spokeswoman for the dissidents claimed that a group within the IRA had abandoned the organisation's avowed aim to uphold the Republic proclaimed in the 1916 and ratified by the First Dail.
It alleged it had no right to allow Sinn Fein to enter the new assembly as this was "in defiance of the constitutional position of Oglaigh na hEireann to uphold the Republic".
It claimed these decisions were taken by a leadership playing "the game of Collins and de Valera" which would ultimately fail because it was not dealing with "the core issue of British occupation".
The statement alleged this position was "a complete betrayal of the claim of Irish national self-determination for which volunteers gave their lives". The spokeswoman said a new "caretaker" army executive had been set up by "volunteers who opposed these constitutional breaches".
The statement called on all IRA members "to remain unified" and return to the traditional republican principles which, it claimed, it was articulating.
It stated that the "ceasefire, as called by the old leadership, is over and our war machine will once again be directed against the British".
It claimed no one had the authority to end the IRA campaign until the British government made a declaration of intent to withdraw from the North.
"A partitionist settlement will not bring peace," the statement said.
In an apparent expression of fear that the mainstream IRA could now move against the new rival organisation and claiming that it had no desire for a feud, the statement said that "all arms under the control of volunteers must be retained solely to challenge the British occupation and under no circumstances be used in conflict among republicans".
A senior IRA member in west Belfast who is loyal to the leadership last night said the dissidents' statement would be strongly challenged by the "real IRA leadership" which remained in firm control of the organisation.