Leading labour movement activists warned yesterday that Prime Minister David Cameron's latest anti-union stunt is a highly dangerous plot to impose even more repressive laws.

The PM has unleashed a six-month "review" into trade union practices amid scurrilous media hype around the Unite union's campaign to save the Grangemouth petrochemical plant.

Bruce Carr QC will consider whether the law needs tightening to prevent trade union "intimidation," declared Tory Cabinet Office Minister Francis Maude.