The number of mobile speed cameras in the UK has risen by more than a third in a year, figures have suggested.
Mobile cameras have less stringent criteria than fixed cameras
The mobile cameras are being used increasingly instead of cameras on fixed sites, and are catching more drivers speeding.
The findings were released by Cyclops, a company which manufactures detectors warning drivers about camera locations.
It said in 2003-2004, 1.8 million fines were issued in England and Wales, seven times the 2000-2001 total.
Cyclops said it had a database of every fixed, temporary and mobile speed camera site in the UK. Criteria for mounting mobile speed cameras were less stringent than for their fixed counterparts.
Cyclops director Steve Wreford said: "At the current rate of growth, we could have as many mobile camera locations as fixed sites by the end of 2005.
"Under the draft Road Safety Bill, motorists caught excessively speeding will receive six points. In other words, that means the average driver could lose their licence and livelihood in just two offences," he said.
More than half of the sites are located on 30mph zones where two-thirds of fatal or serious injury accidents take place.
Department of Transport research has shown drivers travelling 5mph higher than the limit are twice as likely to cause a fatality if they hit someone.
Government rules for mobile speed camera sites rule at least two fatal or serious injury accidents must have taken place in the last 36 months where speed was a significant factor.
A Department for Transport spokesman said: "Speed cameras are only put up at locations where there is a safety record. We know that speed cameras save lives."
Nigel Humphries, spokesman for the Association of British Drivers, said the mobile cameras were merely a way of making money and called for them to be withdrawn.
"The whole thing is driven by revenue and they have to use safety as an excuse," he said.
"If they know there is a camera there they can check their speed. We support fixed cameras that are visible and well known but of course they do not raise much money."