The Crown Prosecution Service (CPS) is to review the convictions of a group of environmental protesters sentenced for planning to shut down the UK's second largest power station.
Some 20 activists were convicted of conspiracy to commit aggravated trespass at the coal-fired Ratcliffe-on-Soar power station in Nottinghamshire.
But the CPS has now announced it is to investigate the "safety" of the convictions, and a QC will be appointed to carry out the review.
The activists all walked free from Nottingham Crown Court with a mixture of community orders and conditional discharges earlier this month.
Two of them - Sarah Shoraka, 33, of Fairholt Road, north-east London, and Ben Stewart, 36, of Alkham Road, north-east London, said their trial may have been a miscarriage of justice.
The CPS move comes after disclosures about the involvement of undercover police officer Mark Kennedy.
Former Met officer Mr Kennedy infiltrated activists' groups across Europe under the name Mark Stone.
The collapse of another case involving six demonstrators, apparently because Mr Kennedy was going to give evidence on their behalf, has led to claims that police withheld secretly-recorded tapes from the defence and the court.
A CPS spokesman said: "We will appoint a QC to consider the safety of the convictions arising from the trial in relation to the Ratcliffe-on-Soar power station protest.
"This will be a thorough review but conducted as quickly as possible."