A concerned resident and neighbourhood watch co-ordinator in Tooting is warning car owners about an increased theft of catalytic converters.

People are using hydraulic machines to lift up the cars before cutting out the catalytic converters and selling the metals inside for money.

Trevor Hutton, of Beclands Road, said he is aware of at least seven vehicles in his ward being targeted, claiming that the car of choice is a Toyota Prius.

Mr Hutton said: "These criminals pretend to be authorised mechanics, they wear overalls and high-vis jackets, they watch cars to know they are left all day, or the driver has gone into a supermarket or business park and they know they will be away for enough time to jack the car up cut through the exhaust pipe and steal the catalytic converter.

"This is not a victimless crime everyone has an excess that they have to pay plus their premiums next year will increase because they may lose their no claims bonus. This also involves unscrupulous scrap metal merchants who pay the criminals for the catalytic converters because they contain expensive heavy metals."

He has urged witnesses to try and take pictures of the 'criminals' and their own vehicle. Met Police confirmed one incident of a catalytic converter theft in December, with Rotherhithe Police also confirming frequent incidents in Southwark Borough.

Mr Hutton said it can cost almost £3,000 to replace the converters.

A catalytic converter is an exhaust emission control device that converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction.