Ex-undercover officer Pc Mark Kennedy has said his "world has been destroyed" after his covert work was exposed.
The case against six green activists accused of conspiring to shut down a power station collapsed after he said he would testify for the defence.
Mr Kennedy told the Mail on Sunday his secret work had "jeopardised" his life.
And he claimed he was now being made a scapegoat for the failure of the trial when, in fact, "a lot of mistakes" were made in the operation's handling.
The former Pc led a double life, serving as a Metropolitan Police officer while posing as an activist known as Mark "Flash" Stone, involved in the green movement since 2000.
On Monday, the trial of six men allegedly involved in a protest at Nottingham's Ratcliffe-on-Soar power station in 2009 was stopped after their defence team asked prosecutors to disclose full details of the officer's activities.
This reportedly prompted the Crown Prosecution Service to drop their case, and the Independent Police Complaints Commission is now examining whether Nottinghamshire Police properly disclosed all relevant material in advance of the trial date.
Mr Kennedy told the Mail on Sunday he believed tape recordings secretly made by him were withheld for fear they would destroy the prosecution's case. BBC News
