Toyota is spending £1 million on a scheme to covertly mark the catalytic converters of more than 100,000 older cars.

The service will be offered free of charge to owners of Toyotas and Lexus vehicles fitted with the exhaust filtration system.

Thefts of catalytic converters have soared in recent years as criminal gangs cash in on the rising value of the precious metals they contain. Police say the thefts are not just petty crime but “a co-ordinated, organised crime linked to other serious forms of offending”.

Thieves are thought to be particularly attracted to certain older Toyota and Lexus models as their hybrid drivetrains mean the metals in their converters are less corroded and therefore worth more money.

In order to help deter thieves and make criminals easier to track, Toyota is working with police forces and Smartwater, the firm which makes police-approved marking kits, to supply an initial 50,000 kits to its dealers.

Toyota and Lexus owners can contact their local dealer to have the marking carried out free of charge but the company is also working with breakdown service the AA and providing 20,000 kits to police forces to help protect owners who may not use the Toyota dealer network.

The markings, which are invisible, mean a stolen catalytic converter can be traced to a specific crime. They also raise the risk to anyone handling the stolen devices, from the thieves to dodgy scrap metal merchants who strip the components down.

Rob Giles, Toyota’s director of customer services, said: “Catalytic converter theft is a very serious problem in the UK and the effects on victims of this crime are emotional as well as financial. We’re pleased to be starting this initiative, working closely with the police, not only to help them with their efforts to combat this crime but also to send a clear message to criminals that if they choose to target a Toyota or Lexus car there is now a far higher chance of getting caught.

“We know from our work with police and others that the solution to this crime is not only arresting those doing the stealing, but also making life harder for those buying the stolen goods. We hope this will help in that.”

Toyota has also restarted production lines in Japan and France that made catalysts for many of the older models, supplying the parts at cost price, and developed a Catloc security device, also fitted at cost price.