Protected witness Charles Bowden told the Special Criminal Court today that he was being held in "conditions contrary to prison law" at Arbour Hill prison.
He claimed that the Department of Justice had refused to deal with the issue of his early release until he had given evidence in the trials connected with the murder of journalist Veronica Guerin.
Bowden, who is serving a six years sentence for drugs and firearms offences, said he was kept locked for 23 hours a day and had no association or recreation until he took legal action to have his conditions improved.
Bowden said he had never felt blackmailed into giving evidence and said he had always told the Department of Justice that his complaints did not affect his willingness to give evidence.
But he said that although he had no problems with the Garda side of the Witness Protection Pogramme, he had been unhappy for some time with the Department of Justice's handling of his case as a State witness.
Bowden said: "They have set aside the merits of my case in qualifying for early release while these trials are going on.
"I always had difficulty with the conditions I was being held under," he said.