The number of fraud cases investigated in the NHS has risen by 37% in the last three years amid the economic downturn, official figures have revealed.

Data from the NHS Counter Fraud Service showed the number of cases of potential fraud detected and probed increased from 351 in 2007-08 to 415 in 2008-09, rising again in 2009-10 to 482.

The value of fraud and unlawful action identified was £4.1m in 2007-8, £16.2m in 2008-9 and £10.9m in 2009-10.

Types of fraud committed varied enormously, the organisation said, but recurrent fraud cases related to staff and professionals claiming money for shifts not worked - known as timesheet fraud - and employees working in unauthorised jobs while on sick leave.

Other categories included patients who might try to avoid paying prescriptions by falsely claiming exemptions or using aliases to obtain drugs; professionals altering prescriptions or creating “ghost patients” and contractors or suppliers attempting to exaggerate records of NHS work.

Allan Carter, head of operations at the NHS Counter Fraud Service, told The Times: “Undoubtedly in times of recession people will look to maximise their opportunities. And when you look at the case numbers it might seem that way.”

He said the service had recovered more than £65m to date.

One case investigated a former senior NHS manager who doctored invoices totalling more than £200,000 to pay for the running of her stud farm business.

Louise Tomkins, 48, of Faygate in West Sussex, was jailed for two years and nine months in June 2010 at Southwark Crown Court.

The court heard she fraudulently signed off NHS payments amounting to £201,333.27 to fund the upkeep of thoroughbreds and pay for horse semen, breaching the trust of her employers.

From April this year, the NHS Counter Fraud Service’s anti-fraud functions that cannot be undertaken locally will be carried out by NHS Protect.

It is envisaged that the new body will provide guidance and assistance to local NHS bodies in dealing with fraud cases.