POWER station bosses said last night they had no knowledge of an environmental protest in Didcot which involved an undercover police officer.

A RWE Npower spokesman said he had “no prior knowledge” of individuals, activities or intentions of protesters who scaled the power station to hang a banner off a tower on July 18, 2006.

It comes as former Metropolitan Police officer Mark Kennedy, who infiltrated a gang of environmental activists under the assumed name Mark Stone, told the Mail on Sunday he was asked to assist with a publicity stunt to hang a banner off a tower in 2006.

No arrests were made. Mr Kennedy was revealed as a covert police officer when a Nottingham Crown Court trial of six people accused of planning to invade Ratcliffe-on-Soar power station collapsed as prosecutors dropped the charges.

Dan Meredith, a spokesman for RWE Npower, said: “RWE Npower had no prior knowledge of individuals, activities or intentions of the group that were involved in the protests, and security operations were co-ordinated by Thames Valley Police.”

Crown Prosecution Service advocate Brian Payne said he believed the Didcot protest was unlikely to have been brought to the attention of the prosecution service as it was peaceful.

He added it seemed to have been dealt with by Thames Valley Police “using their discretion”.

Last night the Oxford Mail asked Thames Valley Police if they knew about the Didcot protest before it happened or that an undercover officer was involved.

Police spokesman Rebecca Webber said she could not answer before the Oxford Mail went to press. But she said: “The role of Thames Valley Police is to facilitate peaceful protests, policing in a proportionate manner and minimising disruption.”

The Metropolitan Police refused to comment.