Aldi withdrew its Today’s Special frozen beef lasagne and spaghetti bolognese products earlier in the week as a precaution. Photograph: Felix Clay for the Guardian
The environment secretary is due to meet the Food Standards Agency, food suppliers and retailers on Saturday to discuss the horsemeat scandal after Aldi became the latest supermarket to confirm its withdrawn beef products contained up to 100% horsemeat.

Owen Paterson said it was unacceptable that consumers were mis-sold products, but that the problems originated overseas.

"We believe that the two particular cases of the frozen burgers from Tesco and the lasagne from Findus are linked to suppliers in Ireland and France respectively. We and the Food Standards Agency are working closely with the authorities in these countries, as well as with Europol, to get to the root of the problem," he said.

Paterson said he believed the food was safe but urged consumers to return products to the retailers. "The French authorities are saying they are viewing the issue as a case of fraud rather than food safety. Anyone who has these products in their freezer should return them to retailers as a precaution.".

Findus denied reports that the company first knew there was horsemeat in its products last year.

"Findus want to be absolutely explicit that they were not aware of any issue of contamination with horsemeat last year," it said in a statement. "They were only made aware of a possible August 2012 date through a letter dated 2 February 2013 from the supplier Comigel. By then Findus was already conducting a full supply chain traceability review and had pro-actively initiated DNA testing."

The Metropolitan police said in a statement it was not carrying out a criminal investigation. "Although we have met with the FSA we have not started an investigation and will not do so unless it becomes clear there has been any criminality under the jurisdiction of the Metropolitan police service."