Black cabs have become the target of a new crime wave, with taxi associations reporting a 50 per cent increase in taxi crime over the past three years.

Police are investigating a series of thefts of cash, radios and receipts from parked taxis in central London. Cabs stuck in traffic and or at traffic lights have also been 'carjacked'.

'Anyone who doesn't lock their doors is in for trouble these days,' said Rodney Lewis, editor of Taxi Globe, the trade magazine.

'In inner London there's a core of about 7,000 cabs which are robbed two or three times a year. Now, on average, a cab is broken into once a year. . .three years ago you had to be unlucky.'

There are more than 17,000 black cabs in London and 22,000 drivers.

Some cabbies suspect that the thefts, often by youths in inner-city areas, are linked to drug use. The thieves, who are after the drivers' takings (sometimes no more than pounds 20 or pounds 30), tend to hang around the filling stations frequented by drivers, and cab shelters - huts throughout central London where cabbies rest and eat.

As the drivers pay for fuel or take a break from driving for a cup of tea, thieves open the often unlocked doors and strip the cabs of cash bags, mobile phones and fire extinguishers.

'These guys are lying in wait and in a few seconds they're off with everything - it's opportunism,' said Bob Oddy, general secretary of the Licensed Taxi Drivers Association.

'Cabbies tend to pop into petrol stations and pay, leaving their takings. It's a bit of a nuisance to have to remove everything from the cab each time the vehicle is left for just a few minutes.'

In New Cross, Hackney, Bethnal Green and Balham, cabs stopped at the lights or caught in traffic jams have been robbed by thieves posing as passengers or beggars asking for change. When the driver opens his passenger window to take directions or hand out cash, the thieves grab his takings and run.

This month a driver in Hackney, talking on his mobile phone, had it ripped from his hands by a young man who knocked on the door, so the driver thought, to ask directions.

According to the RAC, car-jacking in general has greatly increased over the past year.

Scotland Yard, which does not have figures relating specifically to taxi thefts, says licensed cabs are in a high-risk category because they carry cash. They have advised taxi drivers to remove all cash if they leave the car and to lock doors and windows.

But drivers say that the locks on older model cabs are so insecure that such measures, if a thief wants to break in, are almost useless. Many cabs are broken into while parked outside drivers' homes.

'They just break the clips on the windows by pushing them really hard,' said one cabbie who has recently had his radio stolen. 'Break-ins are most definitely on the increase.'

But even the newer more secure models, which have automatic windows and a central locking system, are not much safer.

'I've had three radios pinched since Christmas, once when I was just getting cigarettes,' said Sidney Gilbey, a Metrocab driver from Hackney. 'I won't risk getting another one, it's not worth it.

(Photograph omitted)