Sinn Fein is expected to be back in the Stormont talks on 23 March, following its suspension due to IRA involvement in two murders.
Despite Unionist calls for action, Ms Mowlam said yesterday that she did not plan a further Sinn Fein exclusion despite her security minister saying in a House of Commons written reply this week that he believed "IRA elements" were involved in a third murder - that of Co Armagh man Kevin Conway last month.
During a visit to Londonderry she said she had no conclusive evidence Mr Conway's murder was "IRA authorised".
Ms Mowlam said: "We took action against Sinn Fein on February 20 on everything that had happened before that. Mr Conway was murdered on February 18. We took everything into account and Sinn Fein were excluded. We now, after a period of exclusion, invited them back in."
She said she had acted on the evidence available and she had no more conclusive evidence.
Pressed on whether she would take fresh action against Sinn Fein if she received conclusive evidence of IRA involvement in the Conway murder, she added: "I have no conclusive evidence to suggest that I will take action. I am indicating that I won't."
She said she had no conclusive evidence that the IRA ceasefire has broken. "All the evidence I have suggests it holds."
Her comments fuelled speculation that the IRA leadership has lost control of its north Armagh brigade - always one of the most militant - despite the insistence of the republican movement that it is totally behind the peace process.Reuse content