The dissident republican group, the 32-County Sovereignty Movement, has said it plans to expand in the North and build "the strongest republican opposition ever to British rule".
The statement came as the group opened a branch in Derry at the weekend and claimed it was confident of winning support as "disillusionment" with the Belfast Agreement spread among republican grassroots.
Meanwhile, the first public admission that many dissident republicans have regrouped into a single paramilitary organisation, calling itself Oglaigh na hEireann, came at a function for anti-agreement prisoners in Derry at the weekend.
Messages were read out from "Real IRA" prisoners in Britain and men awaiting trial for what security sources believe was a Continuity IRA attack on an RUC station in west Belfast.
The Northern inmates said they wished to be known as "Irish Republican Army" prisoners and voiced support for "Oglaigh na hEireann".
The sovereignty movement branch in Derry was opened by the organisation's chairman, Cllr Francie Mackey. Speaking at a meeting in the city, he said: "We plan to develop the strongest republican opposition ever to British rule in Ireland.
"Republicans, now more than ever, must unite to ensure the damage already done by participation in Stormont is halted. We said this process would not deliver. We were right. It was sold as a `peace' process. There is no peace.
"I am confident we are growing from strength to strength. The republican position has not changed and we have growing support across the country." Mr Mackey said the Patten report would be rejected by all true republicans.
Around 150 people attended the function for anti-agreement prisoners.