Screens should be in all buses by the spring

The technology will offer so-called "digitally-watermarked" images in a format which can be used in court by the Crown Prosecution Service.

Buses on route 36, from Lewisham to Queens Park, and buses on route 12, from Dulwich to Notting Hill, will be the first to be fitted.

A further 170 buses will be fitted soon afterwards in east London.

The scheme is the result of a link between the Metropolitan Police, London Central Buses and the technology firm, CrystalEyes Ltd.

'Passengers safer'

PC Raymond Webb, co-ordinator of the Metropolitan Police's Operation Seneca, which targets bus crime, said: "A lot of the worst murders of our time have had some relationship with buses and if you have this on a bus it's going to help.

"It will also help with criminal damage and graffiti and help passengers to feel safer."

It is hoped that the technology will be installed on every London bus by the end of spring next year.

The kit for each bus costs �8,000, but it hoped the running costs will be provided through advertising revenue.

Ross McDonald, from Covent Garden-based CrystalEyes Ltd, said: "We're starting off with 50 screens reaching 20,000 passengers a day.

"That should rise eventually to 225 screens showing images to 170,000 passengers a day."

PC Webb said it is expected that every bus in the capital to be using a similar system within five years.