Town hall snoopers used controversial anti-terror powers to delve into the phone and email records of thousands of people last year. They wanted to check for evidence of dog smuggling and storing petrol without permission - and even to trace a suspected bogus faith healer.

In one case they were inquiring into unburied animal carcasses.

Some councils are allowing middle-ranking staff to authorise covert operations under the controversial Regulation of Investigatory Powers Act, which is intended for use 'in the interests of national security'.

The Home Office said a person investigated using the Act would not be told by a council. It would only come to light in the event of a prosecution.