Internet café owners are being asked to spy on their customers as part of the Met police's terrorism prevention efforts.

Under a pilot project in Camden some have agreed to monitor their customers' internet habits for evidence of interest in Islamic extremism, the BBC reports. They are intalling police screensavers and putting up posters warning against visiting extremist websites.

The intitative is part of the Prevent strand of the government's counter-terrorism strategy, which aims to stop radicalisation by winning the "battle of ideas". Café owners are asked to use their own judgement as to what amounts to extremist material.

The focus on internet cafes follows the conviction last year of the liquid bomb plotters, who planned to blow up passenger jets by mixing chemicals disguised as soft drinks. They used public cafés to anonymously access extremist websites and communicate with each other.

Arun Kundnani of the Institute of Race Relations described the initiative as "dangerous".

"It... potentially criminalises people for accessing material that is legal but which expresses religious and political opinions that police officers find unacceptable," he said.

"It is likely to result in not only a general violation of privacy and freedom of expression but also discrimination against Muslims, whose use of the internet will be seen as inherently more suspicious."

Other parts of Prevent have been criticised for alienating Muslim communities from the police. It has also been alleged that funds meant to support moderate Islamic groups have been diverted to extremists. ®