Fraud investigators at Harrow Council have explored more than 600 allegations of fraud over the past two years.

The bulk of their work, 433 cases, concerned suspect benefit claims, for instance, those in which recipients failed to declare a change of address, disclose income or savings, or reveal a change of circumstances.

Between January 1 2007 and November 24 2008 - the latest period for which information is available - 48 individuals were prosecuted for their deceit by Harrow Council or by the Department for Work and Pensions.

The statistics, obtained by the Observer through the Freedom of Information Act, show that in 78 cases, the target of the probe was slapped with an administrative penalty, meaning he or she had to pay back the full sum claimed plus 30 per cent of this amount as a fine. A further 29 people were cautioned for what they did.

Not all investigations were successful though. Insufficient evidence forced Harrow Council's anti-fraud team to close 27 files and in 102 instances, no evidence of fraud was found.

The investigators are also responsible for probing the authority's own workers, sup-pliers and contractors, and they have wrapped up 196 such corporate fraud cases in the last two years.

As a result, one employee was convicted of fraud in August 2007 and another four months later. In October 2007, an employee resigned or was sacked due to a dishonesty investigation.

In four other occurences, authority workers were dealt with under the internal disciplinary policy - one in February 2007, two in January 2008 and one the following month. Investigators wound up one case because they were unable to prove fraud had taken place, and shut a second following an assessment that deemed the information too weak or unreliable for the case to proceed.

Suspicions were followed up in 162 applications from residents for non-benefit claims such as council tax discounts, student awards, disabled blue badges for cars or the over-60s' Freedom Pass.

However, the council found no evidence of fraud in 78 of them and was unable to prove any-thing was amiss in 37 others.

Forty-four cases were rejected because of doubts over the quality or source of the tipoff, and the only prosecution in this category since January 2007 was a false homeless housing application in November.

Companies also caught the anti-fraud team's eye. In October 2007, and again in April 2008, the council probed allegations of a contractor acting fraudulently, but dismissed them the same day as there was no evidence of any misdemeanour.

Meanwhile, a 10-month investigation into a firm supplying services was dropped in February when the council was unable to prove fraud, and a probe launched in October into alleged fraud involving the council's construction contractor Kier and its sub-contractors is expected to be published in January.

Council leader David Ashton (Conservative), said: "We have been rated as a top-performing benefit team, recognising the fact that we have been catching a high rate of benefit cheats, especially within the last couple of years.

"It is our priority to ensure honest taxpayers are getting their money spent on services that benefit them. That is why we are always striving to catch those who claim benefits fraudulently.

"Thanks to the Voice Risk Analysis system, we are able to detect more cheats. This has saved us around £700,000 in benefit fraud and discourages those attempting to cheat the system."