Mark Kennedy says he has been 'hung out to dry' by former employers

The former policeman who spent seven years undercover among environmental activists has denied being an agent provocateur, saying that his superiors knew exactly what he was doing at all times and approved his activities.

Mark Kennedy, a Metropolitan police officer who infiltrated green and anarchist groups under the alias Mark Stone and fled to America after his cover was blown, said he fears for his safety following threats from activists. The 41-year-old said he believed that his former police superiors were looking for him too.

"I can't sleep. I have lost weight and am constantly on edge. I barricade the door with chairs at night. I am in genuine fear for my life," said Kennedy, who sold his story to the Mail on Sunday. "People like to think of things in terms of black and white. But the world of undercover policing is grey and murky. There is some bad stuff going on. Really bad stuff."

However, Kennedy said that throughout his time spent undercover he was in constant touch with police handlers and never tried to push fellow protesters into taking action: "I had a cover officer whom I spoke to numerous times a day. He was the first person I spoke to in the morning and the last person I spoke to at night. I didn't sneeze without a superior officer knowing about it. My BlackBerry had a tracking device. My cover officer joked that he knew when I went to the loo."

He said he felt he had been "hung out to dry" since being exposed.

Kennedy's activities were at the centre of the decision last week by prosecutors to abandon the trial of six activists accused of conspiring to break into Ratcliffe-on-Soar coal-fired power station in Nottinghamshire.

The former officer said that he made undercover audio recordings of the activists which threw doubt on prosecutors' claims they had conspired to commit aggravated trespass, but that his police superiors chose not to pass these on.

He said: "The truth of the matter is that the tapes clearly show that the six defendants who were due to go on trial had not joined any conspiracy. The tapes I made meant that the police couldn't prove their case. I have no idea why the police withheld these tapes."

The Independent Police Complaints Commission is to investigate the collapsed case. Twenty other environmental activists previously found guilty in connection with the same protest at Ratcliffe-on-Soar plan to challenge their convictions.

There have been calls for a wider investigation into the way police infiltrate such groups. Kennedy said that he knew personally of 15 other officers hidden within green groups during his time undercover from 2003 to 2009. He said: "Some got busted, others left. I was the longest-serving operative. At the time I left in 2009, there were at least four other operatives. I never did anything to jeopardise the work or lives of my fellow officers and I will not start now."

Kennedy, who separated from his wife in 2000, said his children, a girl aged 10 and a boy of 12, have been left devastated by recent events.

One of the most controversial aspects of his story is that he conducted at least two sexual relationships with fellow activists while living as Mark Stone. This, he conceded, should not have happened: "I am the first one to hold up my hands and say, yes, that was wrong. I crossed the line."

The relationships symbolised the impossible position in which he felt he had been placed, Kennedy added, admitting that the longer he spent with the activists the more he began to sympathise with their causes.

He said: "I fell deeply in love with the second woman. I was embedded into a group of people for nearly a decade. They became my friends. They supported me and they loved me. All I can do now is tell the truth. I don't think the police are the good guys and the activists are bad or vice versa. Both sides did good things and bad things. I am speaking out as I hope the police can learn from the mistakes they made."

"I was at the heart of a very sensitive operation. I was told my work was the benchmark for other undercover officers. My superior officer told me on more than one occasion, particularly during the G8 protests in Scotland in 2005, that information I was providing was going directly to Tony Blair's desk."

He continued: "As the years went on, I did get a sort of Stockholm syndrome. But I never lost sight of my work. I texted and informed on a daily basis. But I began to like the people I was with. I formed lasting friendships."

He criticised what he said was a lack of psychological support from his employers, saying he had considered killing himself in recent months: "I was supposed to get psychological counselling every three months. I would go two years without seeing the shrink. Initially meetings were regular. Then it became a farce. The office was so greedy for intelligence that they didn't set up the meetings. They went by the wayside. I'm sure that's the same for other undercover officers too." He said he resigned from the police last year.

Kennedy, who joined the City of London police aged 21 before moving to the Met, said that in 2006 he was beaten up by uniformed fellow police near Drax power station in North Yorkshire after trying to protect a female activist being struck with batons.

"I tried to stand between her and him. I didn't do anything aggressive. That's when I got jumped on by five officers who kicked and beat me. They had batons and pummelled my head. They punched me. One officer repeatedly stamped on my back."

Kennedy also told how he had created a credible identity when infiltrating groups, which included claiming a background in drug smuggling. He had formerly worked in the Met's drug squad.

He said: "I was an avid rock climber and I had been to Pakistan so I created a story about being involved in the importation of drugs. I knew the London drug scene well so I purported to be a courier. That is how I justified having money."