Media playback is unsupported on your device Media caption Martin Corey spent almost four years in jail without trial after his licence was revoked in April 2010

The prominent Irish republican, Martin Corey, has been released after almost four years in prison without trial.

He had been held in Maghaberry jail since April 2010 without any charges being brought against him, after he was deemed to be a risk to the public.

The Republican Sinn Féin member is a convicted double murderer.

Corey 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.

On 27 February, 1973, Corey and two other IRA members ambushed police officers in Aghalee, County Antrim.

One officer, Constable Raymond Wylie, was killed instantly. Constable Robert McCauley died on 25 March 1973.

Corey was re-arrested at his home in Lurgan, County Armagh, on 16 April 2010 for alleged involvement with dissident republicans and had been in custody since that date.

'Unspecified allegations'

He was told he was being sent back to jail 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.

Former Northern Ireland Secretary of State Shaun Woodward had ordered his prison recall on the basis of "closed material" and unspecified allegations of involvement with dissident republicans.

Corey's supporters claimed he was being interned without trial and launched a campaign to secure his release.

Last May, his lawyers said they would challenge his detention in the European court.

Corey was released from custody on Wednesday evening, following a decision by the Parole Commissioners for Northern Ireland.

He left Maghaberry prison in an unmarked van at about 20:00 GMT.

Image caption Corey had been held in Maghaberry Prison

It is understood the conditions of his release include a ban on speaking to the media.

Members of the Free Martin Corey Campaign have told the BBC they had 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."

'Stark contrast'

In a statement, a spokeswoman from the Northern Ireland Office (NIO) said that "the independent Parole Commissioners for Northern Ireland have issued their judgment in respect of Martin Corey".

"The Parole Commissioners have decided to release Martin Corey on a licence that is subject to conditions which are designed to manage the risk they assess him to pose," the NIO spokeswoman added.

Ulster Unionist Tom Elliot said the decision to release Corey followed the warning issued to Sinn Féin's Gerry Kelly for clinging to a police Land Rover and the suspended sentence given to Old Bailey bomber Marion McGlinchey.

"The treatment of McGlinchey and Kelly was in stark contrast to the heavy sentences handed down to many non-republicans in recent months feeding the perception that the justice system is being very, very lenient towards republicans," he said.

"The decision of the Parole Commissioners to release convicted double murderer Martin Corey, whose licence was revoked in 2010, will only add further weight to that perception.

"To release Corey at a time when the security services still face a severe threat from republicans still wedded to the failed strategy of physical force seems curious."

However, Corey's solicitor, Peter Murphy said: "We're delighted that he's been released, it's been a long hard crusade for us in seeking his release

"He never knew the reason for his detention in any specific detail, he never was able to face his accuser."

'Human rights'

Corey's release has been welcomed by Sinn Féin but the party said the government has "lessons to learn from his imprisonment".

Sinn Féin MLA Jennifer McCann said: "At no time was he questioned by police or were his legal team shown evidence against him.

"At no time was due process had. This was a clear abuse of Martin Corey's human rights and is an indictment on those who held him," Ms McCann said.

Corey's party, Republican Sinn Féin, was formed in 1986 following a split with the Sinn Féin leadership.

The roots of the fallout were over Sinn Féin's decision to take seats in the Irish parliament, thus ending its policy of abstention in the Republic of Ireland.