Freed hostage Harmeet Sooden has said he believes a ransom was paid for his release.

Mr Sooden, who was held captive in Iraq for four months, said today that he and his fellow hostages thought their rescue was "contrived".

The Auckland student, who is a Canadian citizen, said he was grateful to the New Zealand and Canadian authorities for their assistance, but said the invasion and occupation of Iraq were "illegal" and the New Zealand government was complicit in that.

Mr Sooden, 32, a member of activist organisation the Christian Peacemakers Teams (CPT), described how he and his two fellow captives were released on March 24. He said they heard unusual noises and then an English accent demanding the door be opened.

Within moments British soldiers were cutting them free. Another soldier wearing a mask removed it to show he was an Iraqi, a move Mr Sooden said he thought was supposed to indicate the Iraqis were involved in the rescue.

His captors were "nowhere to be seen" during the release, which was "highly unusual", he said.

"I felt it was contrived," he said. Asked if he thought a ransom was paid, Mr Sooden said it was "highly probable" though he had no evidence for that.

Mr Sooden said the taking of hostages such as himself, fellow Canadian James Loney, 41, Briton Norman Kember, 74, and American Tom Fox, 54, was "simply a way to fund the insurgency". He added: "I wanted to be released, but I didn't want money to be paid.

"Our belief was that we were commodities to be exchanged for money and that if that didn't work out or there was a raid, we would be destroyed."

He said videos other than ones released to Arabic television channels during his captivity were filmed. Since his release, Western authorities had given "vague information of what happened to them", indicating they had been used in negotiations.

Mr Sooden remained calm and measured throughout an hour-long press conference in Auckland this afternoon except when talking about Mr Fox, who was killed and his body found dumped in Baghdad earlier this month. At those moments he stopped to compose himself and shed a tear.

"I never had any regrets, even during the worst moments, which surprised me," Mr Sooden said. "I never felt I should not have gone." He said he would consider returning to Iraq to do peace work.

Mr Sooden described how the hostages were kept bound and hooded for the first week and were only given six biscuits and two small glasses of water a day. However, conditions improved during their time in captivity.

He said he was slapped once and guns were sometimes pointed at the hostages.

But he saw his captors as "victims" who had suffered at the hands of the American-led invasion of Iraq. One of their captors brought them food and offered to clean their clothes, while another was more volatile and tension rose when he was present.

Mr Sooden said he now struggles to sleep and is not eating well, but hopes that talking about his experiences will help him to relax.

He said he would take New Zealand citizenship if offered.