A senior scientist has told Sky News that lamb products may also contain horsemeat and need to be tested.
Dr Mark Woolfe, formerly of the Food Standards Agency, said retailers should immediately test everything from lamb ready meals to doner kebabs for horse DNA to ensure their products are clear.
He warned the same pressures to find cheap sources of beef make it impossible to "verify" the lamb supply chain.
Dr Woolfe was in charge of the "food authenticity" unit at the FSA for 17 years and is widely respected for his research.
He said: "If I was a retailer I would be looking quite carefully at my lamb products as well.
"When I ran the surveillance programme, the only time I would say there was a problem was when I found a problem.
"That's why I say it would be diligent for people to look at other products."
Dr Woolfe blamed the current horse meat scandal on a sudden change to European Union rules last year that affected economy meat products.
For more than a decade manufactures rubbed the remaining scraps of meat from animal carcasses to make a fine mince called de-sinewed meat (DSM). It was the primary ingredient for cheap pies, sausages and ready meals.
But the EU decided last spring that DSM could no longer be used, forcing suppliers to find an alternative source of cheap meat within a matter of days.
"It left suppliers with big hole in their supply chain for the raw materials for their value products. They had to look elsewhere for product at same price or cheaper to fill that gap.
"If that can't be done in this country then they go abroad.
"If something is produced in the UK they have better control over the supply chain. It's more difficult to verify the supply chain outside the UK."
The warning comes after an expanding international scandal over processed beef products, which were found to contain up to 100% horsemeat.
The Environment Secretary is to hold another round of talks with the food industry to discuss the scandal.
Owen Paterson has told MPs that it appears "criminal activity" is at the heart of the scandal that has spread across Europe.
He will hold talks with the Food Standards Agency (FSA) and food industry representatives tonight in what will be the second UK summit in a matter of days.
Supermarkets were forced to remove certain beef burgers and ready-meals such as spaghetti bolognese after details of the adulteration were exposed by Irish food safety officials.
Controversy and concerns about traceability of food deepened in early February when halal food supplied to prisons by a Northern Ireland-based company was found to contain traces of pork DNA.
It emerged that a number of ready meals including Findus beef lasagne, made in France and distributed across UK supermarket chains, contained up to 100% horsemeat.
One of Findus' main shareholders has told Sky he thinks the company have handled the public relations aspect of the crisis poorly.
Initially, suppliers in Poland were accused of replacing beef supplies with horse products, however the supply chain was later said to have used meat sourced in Romania.
The French supplier to Comigel, the ready meal giant which made the Findus and Aldi dishes found to contain up to 100% horsemeat, appeared to point the finger at two Romanian slaughterhouses.
But a preliminary investigation by the Romanian government claimed that the paperwork from the abattoirs was in order and that the livestock entering the facilities were accurately documented.
Romanians reacted angrily to the claims.
Sorin Minea, head of the Romanian food industry federation Romalimenta, told Sky News that the accusations are tinged with racism: "Look at the thief in the square, the gypsy. He is to blame."