The trial of six green campaigners has collapsed amid claims that an undercover policeman who infiltrated their group offered to give evidence on their behalf.
The six were charged with conspiring to shut down the coal-fired Ratcliffe-on-Soar power station in Nottinghamshire in 2009.
Their case was due to be heard this week, but has been abandoned after the officer apparently contacted the defence team to say he would be prepared to help.
A statement from the Crown Prosecution Service (CPS) said the new information, which led to the collapse of the trial, was “not the existence of an undercover officer”.
The new details came to light on Wednesday, January 5th, and the CPS then decided there was no longer sufficient evidence for a realistice prospect of conviction.
Hundreds of activists were arrested when police raided the Iona School in Sneinton, Nottingham, on the morning of Easter Monday, April 13, last year.
The protesters planned to trespass at the local power station and shut it down for a week, a trial at Nottingham Crown Court heard.
The undercover officer involved has been named as Pc Mark Kennedy, a former member of the Metropolitan Police who has spent the past seven years undercover in the environmental protest movement. He is said to have recently resigned from the force and moved abroad.
Some activists have claimed that his role went beyond that of a police observer and that he helped fund the protest and planned to take on a main role in disrupting the power station.
Earlier this month 20 protesters were sentenced to a mixture of community orders and conditional discharges after they were convicted of conspiracy to commit aggravated trespass at Ratcliffe.
The Met Police said it was “not prepared to discuss Mr Kennedy.”
