Dr Mowlam, responding to unionist criticism of the decision, nonetheless described the move as a "necessary step" to support the peace process.
"I apologise for the hurt I have caused people, particularly those families and friends of victims who find it difficult. But I hope we can keep moving forward and make sure that the vote on May 22nd means there is a better future for everybody," she said in Belfast yesterday.
It was a difficult decision to take but what was important "in the broader picture" was to ensure that the process could continue to be moved forward inclusively.
Earlier she told BBC Radio 4's Today that the temporary releases were "a necessary step to take to convince people of the value and importance of the agreement which I think it has helped achieve".
"Therefore, in the long term, I think it's worth it. But I understand how difficult it is for people when they see it," she added. There would be "no other significant releases of this nature".
Mr David Trimble, leader of the UUP, complained that the releases would have a "negative impact".