A road safety campaigner has questioned how many drivers have been prosecuted for speeding in the M62 roadworks area after police refused to reveal how many have been snared by speed cameras.

West Yorkshire Police has denied a request under the Freedom of Information Act asking it to supply the number of motorists prosecuted for speeding between junction 25 at Brighouse and junction 30 at Rothwell since a 50mph zone has been in force. It claimed releasing the data could give the impression that the chances of being caught in certain locations is low, encouraging higher speeds and causing more accidents.

But Brighouse road safety campaigner Carole Whittingham, who set up the charity Support and Care After Road Death and Injury (SCARD) after her son Steven was killed by a drink-driver in 1992, said publicising the information could act as a deterrent to drivers if people are being caught.

“They don’t have to say which areas people have been caught in, but the number of drivers found speeding in the roadworks. The only way I can see it would be harmful would be if they hadn’t caught anyone,” she said.

Police had been asked to supply information about the number of intended prosecutions that had been issued since the managed motorway scheme began, the number that resulted in prosecution and what the lowest speed for prosecution was.

But a spokesman for the West Yorkshire Casualty Reduction Partnership refused to give the information, claiming it could “prejudice any future enforcement policy”.

“For speed enforcement to be truly effective there must be the perception that the chance of being recorded is high at all sites,” he said.

“Releasing site-specific data may identify those sites where a motorist is more likely to be caught exceeding the speed limit. This may, in turn, reduce the effectiveness of those sites where motorists perceive there is less chance of being caught, resulting in an increase in speeding and speed-related incidents and casualties.”

Meanwhile, Morley MP Ed Balls has confessed he was caught speeding on the M62 in West Yorkshire.

The shadow chancellor said he was doing 56mph in a 50mph zone. He said he had paid a fine and attended a speed awareness course rather than accept penalty points.

"Like many local people, I was caught out by the never-ending roadworks on the M62. Pulling on to the motorway at Morley I realised too late that the speed restrictions were still in place,” the Labour MP wrote on his blog.