A Car is broken into every hour in Bristol, police figures show.Avon and Somerset police say thieves are targeting cars for items such as satellite navigation systems.

Force figures show 170 cars are broken into in the city every week, with an average 12 sat nav systems stolen.

Sat nav units are expected to be popular Christmas presents this year. The systems are programmable to give drivers directions to their destination.

Many off-the-shelf makes attach to a car's windscreen by suckers, which if left behind can be an invite to thieves, say police.

Windscreen repairer, Darren Jefferies, 38, of Wick, who works for RAC Auto Windscreens, called the Evening Post after his own unit was stolen.

He repairs cars after they have been broken into.

He said: "I've been told that in the past week there have been more than 40 sat nav systems stolen from vehicles which have been broken into.

"I was told about a lorry driver who had an accident and got out, and by the time he got back in his cab, the unit had been stolen."

Many people left their systems in glove compartments and under seats, he said, where thieves knew they would hide them.

Others simply would not tell the police about thefts of sat navs from their vehicles, he added.

While Mr Jefferies was out working on a vehicle in St Philip's, his sat nav system was taken from his van.

He gave chase, but the thief was on a bicycle and got away.

Darren Bane, a spokesman for Avon and Somerset police, said the force was encouraging sat nav owners to log on to a registering website called Immobilise.

There they could enter the details of their system and if it was stolen, they could be reunited with it if it was found.

He said: "I suspect sat navs are something on a lot of Christmas lists this year. If it has a serial number, it can be registered on Immobilise.

"Particularly in somewhere like Bristol, you don't know where it could end up.

"By registering it, that kind of thing is not such a problem."

He encouraged people not to leave the systems and their brackets suckered to their car windscreens. Such things automatically made cars a target for thieves, he said.

A recent poll by car windscreen repair specialist Autoglass showed one in 10 people in the Bristol region had had their cars broken into in the past two years. Of those, 40 per cent had gadgets such as sat nav systems stolen.

The figures showed the thefts cost motorists in the region up to £9.4 million a year. The company estimated sat navs were being sold on by thieves for as little as £50 each. Nigel Doggett, the managing director of Autoglass, said: "One third of sat nav owners also admit to leaving the cradle on display, while one in 10 simply leaves the system in place when they park. This is effectively offering an open invitation for thieves to strike. The only way to prevent a break in is to remove all trace of the equipment from the vehicle."

Log on to www.immobilise.com for more information on registering.