Prominent republican Martin Corey has been released from Maghaberry prison.
It is understood he was freed after a decision by secretary of state Theresa Villiers.
Corey, a member of Sinn Féin, was released from custody last night and left Maghaberry prison through a back entrance in an unmarked van.
It is understood the conditions of his release include a ban on speaking to the media.
Corey had been held in the jail without trial or charge since April 2010, after he was deemed a risk to the public.
He was rearrested at his Lurgan home and had been in custody since that date.
Corey, from Lurgan, Co Armagh, is a convicted double murderer.
He was originally sentenced to life in prison in 1973 for his part in the IRA murders of two police officers, but was released on licence in 1992.
Sinn Féin MLA Jennifer McCann welcomed his release but said the British government had lessons to learn from Corey's imprisonment.
"At no time was due process had," she said. "This was a clear abuse of Martin Corey's human rights and is an indictment on those who held him.
"Sinn Féin have consistently raised this issue and the conditions under which Martin Corey was detained. I am glad that he is now released and free to return to his family.
"There are very clear lessons which present themselves to the British government. The arrest and detention of people without any evidence being presented cannot be justified in any terms."
At the time of his arrest he was told he was being sent back to prison because he was considered a risk to the public, but at the time neither Corey or his legal team were told why the authorities believed he posed a threat.
When the case was referred to the Parole Commissioners in 2011, they could have directed his release if they "were satisfied that it was no longer necessary for the protection of the public from serious harm that he should be confined to prison".
They refused to do so, saying they were not satisfied that his detention was no longer necessary for the protection of the public.
Corey's supporters claimed he was being interned without trial, and launched a campaign to secure his release.
His solicitor, Peter Murphy, said: "It's like internment all over again in the sense that he hasn't been given the chance to defend his position.
"When we ask questions about the nature of the allegations and evidence against our client we are told nothing.
"In any criminal court you can meet your accuser, you have a chance to cross-examine them, and you have a chance to defend yourself because you're given the detail of what the allegations are against you.
"We don't have any of that, so our client is in a very difficult situation in that he's sitting in prison not knowing why he's there."
Last May, his lawyers said they would challenge his detention in the European court.
Members of the Free Martin Corey Campaign have said they have concerns about the manner of his release.
A campaign spokesperson, Cait Trainor, said: "It is clear the continued imprisonment of Martin Corey was a political embarrassment to the Northern Ireland Office and he was released in a way that would ensure minimum publicity."