A LEADING food safety expert claims restaurants have been substituting cheap beef for lamb for years, after a report revealed one-third of curry houses north of the Border are guilty of the practice.

Sir Hugh Pennington, who chaired the public inquiry into the E.coli outbreak in Wishaw, North Lanarkshire, in the 1990s, spoke out after a leaked document showed low-quality beef was being passed off as lamb in more than 30% of all curries tested by the Food Standards Agency (FSA) in Scotland.

Investigators who sampled food for 18 months found lamb was substituted by beef in bhoona and korma dishes in 46 of the 129 restaurants tested.

In 33 eateries there was no lamb in the dishes at all, while the remaining 13 used some lamb in combination with cheap cuts of beef.

Sir Hugh, emeritus professor of bacteriology at Aberdeen University, said: "There's been intelligence about it for a number of years, so there's nothing new about it. Quite a large amount of testing has been done, which has shown the scale of the problem. It's a bit like the horsemeat issue – it's fraud. Rather than one or two traders in Europe defrauding people, this is local and on a grander scale."

The FSA's report added: "The results confirm significant lamb-based curries offered for sale in Indian and other similar-style restaurants and takeaways were falsely described as they contained either no lamb or a mixture of lamb and meat.

"A significant minority of food business operators appear to be intentionally mis-describing food."

The Scottish Food Enforcement Liaison Committee, which is part of the FSA, has not named the guilty restaurants.

The findings come in the wake of price rises that have seen the cost of lamb rising to around £9 a kilo, in comparison to beef which costs about £5 for a similar amount.

Sir Hugh said the substitution was not dangerous to customers as long as the beef was obtained from a reputable source and had been cooked properly. However, he added: "It raises questions not just about fraud, but about other issues.

"How good are their practices in the kitchen, if they're defrauding customers? How safe are they in other aspects?

"So I think the local authorities, who are primarily responsible for regulation – although the Food Standards Agency has an overarching responsibility – have to come down on these premises hard."

John Sleith, chairman of the Society of Chief Officers of Environmental Health in Scotland, said: "There clearly is a problem with beef being substituted for lamb. Customers aren't getting what they asked for but a cheaper, inferior product. All of those businesses were warned that further random sampling would take place and any future offences would be reported to the procurator-fiscal."

Enam Ali, chairman of the Guild of Bangladeshi Restaurateurs, said: "It is another blow at a time when the food industry is trying to regain the confidence of its customers. It is simply not acceptable."

Foysol Chowdhury, president of the Scottish branch of the Guild of British Restaurateurs, said of the restaurants: "They are doing the reputation of our restaurants down."

l SNP MSP Angus MacDonald has called for the new supermarket ombudsman to conduct an investigation into the pressure supermarkets put on meat processors.

Members of Holyrood's Rural Affairs and Environment Committee have written to Christine Tacon asking her for an investigation into the relationship between supermarkets and the meat-processing sector.