Covert police officers are �infiltrating protest groups and offering activists payments for intelligence, it has been claimed.

Carolyn Churchill and John Bynorth

Covert police officers are infiltrating protest groups and offering activists payments for intelligence, it has been claimed.

The allegation emerged after a member of the Plane Stupid organisation who was arrested after the protest at Aberdeen Airport last month was approached by two men claiming to be from Strathclyde Police.

They offered her money to pass on information and claimed they had "hundreds of people" who were acting as informants from within environmental organisations, as well as left-wing, right-wing and terrorist groups.

Last night, civil rights campaigners said the tactic was "not healthy in a democracy".

Matilda Gifford, an activist with Plane Stupid, recorded her conversation with the men, who told her they were from the "community intelligence section" of the police, on two occasions, first at a police station in Glasgow and the second time at a prearranged location on the street.

They suggested that she could receive "tax-free" money to help pay off student loans if she gave them information and advised her to take cash in hand rather than have the money paid into a bank account "because that leaves an audit trail - and an audit trail can compromise you".

Ms Gifford's lawyer, Patrick Campbell, said: "I have very considerable concerns about these events. There appears to be a covert operation that is running in some way with, or using Strathclyde Police's name.

Ms Gifford, who is yet to stand trial in connection with the protest at Aberdeen Airport, said that all members of Plane Stupid were committed to non-violence.

She told The Herald: "I think it is completely unjustified and unwarranted that taxpayers' money is paying for information to bust actions or for intimidation techniques to influence people to move away from protest activity. It is really sinister and says a lot about how our justice system works."

Geraint Bevan, co-ordinator of NO2ID Scotland, said: "It is the police's job to police protests, not to manage them so they do not happen. They need to accept that people have the right to choose to break the law and take the punishment which comes with that."

Assistant Chief Constable George Hamilton, of Strathclyde Police, said: "Strathclyde Police has pledged to make communities safer and, as such, has a responsibility to gather intelligence to enable them to do this.

"This responsibility is discharged in accordance with the relevant legislation ensuring that the action of its officers comply with the legislative requirements of the Regulation of Investigatory Powers Act 2000 and the Regulation of Investigatory Powers (Scotland) Act 2000, and the relevant codes of practice.

"Officers from Strathclyde Police have been in contact with a number of protesters who were involved with the Plane Stupid protests including Aberdeen Airport.

"The purpose of this contact has been to ensure that any future protest activity is carried out within the law and in a manner which respects the rights of all concerned."