TWENTY-NINE people convicted of crimes after a power station protest where a Metropolitan Police officer was working undercover can appeal against their convictions, the Director of Public Prosecutions said today.

Keir Starmer said there were concerns about the safety of the convictions obtained following the Drax Power Station protest in North Yorkshire in 2008.

He has also asked the Metropolitan Police to examine records of all operations involving Mark Kennedy which led to convictions.

The actions of Kennedy, who spent seven years posing as long-haired drop-out climber Mark "Flash" Stone, led to the collapse last year of the case against six protesters accused of planning to invade the coal-fired Ratcliffe-on-Soar power station in Nottinghamshire and led to a review of police undercover tactics.

Mr Starmer said he was inviting those convicted after the Drax protest to appeal after a review of the case by a senior CPS lawyer and after taking advice on the safety of the convictions from a senior QC.

"Having considered the conclusion of that review carefully, I have decided that the safety of the convictions should be considered by the Court of Appeal.

"That is because it appears to me that a senior CPS lawyer, who has since left the organisation, may not have complied fully with disclosure obligations in this case.

"The prosecution cannot lodge an appeal in these circumstances, so I have taken the unusual step of writing to the legal representative of those convicted, inviting them to appeal on the basis of non-disclosure of material relating to the activities of the former undercover officer, Mark Kennedy.

"The safety of the convictions is a matter that can only be dealt with by the Court of Appeal."

Mr Starmer said he had asked Sue Hemming, the head of the CPS Special Crime and Counter Terrorism Division, to work with the heads of its complex casework unit to go through records and find out if "there are any further cases involving undercover officers that might need to be examined".

He had also signed a memorandum of understanding with police and other investigative agencies, including the Association of Chief Police Officers, the Serious Organised Crime Agency, HM Revenue and Customs and the CPS, in a bid to ensure information about undercover officers is shared between investigators and prosecutors and disclosed to the defence when required in future cases.

In April, police officers escaped misconduct proceedings for keeping Kennedy's presence secret during the collapsed prosecution of activists accused of plotting to shut Ratcliffe-on-Soar.

"Collective failings" were to blame for Nottinghamshire Police not disclosing his undercover role, the Independent Police Complaints Commission ruled.

The watchdog found that "the actions of individual police officers and members of police staff did not amount to misconduct" during the Ratcliffe-on-Soar case.

"Because I have real concerns about any prosecutions involving Mark Kennedy, in April I asked the Metropolitan Police Service to examine their records relating to Mr Kennedy's deployment to confirm that the Criminal Procedure and Investigations Act 1996, which sets out disclosure obligations, was adhered to," Mr Starmer said today.

"The MPS has agreed to that request and is currently engaged in that exercise.

"What happened in cases involving Mark Kennedy cannot be allowed to happen again."