Horse DNA has been found in cottage pies sent to 47 schools in Lancashire, it has emerged, proving for the first time that horse meat has found its way into British school dinners.

The council's own laboratory has been carrying out DNA tests on samples collected by its trading standards officers, and preliminary results show the presence of horse DNA in the school meals, which have been withdrawn.

Tom Walker, a spokesman for the council, said the samples would now be sent off to the Food Standards Agency for more thorough tests which will show what proportion of the meat is horse meat rather than beef.

In a statement the council said: "Lancashire County Council has withdrawn a beef product from 47 school kitchens after it provisionally tested positive for traces of horse DNA.

"The provisional results of the tests on a pre-prepared cottage pie from an external supplier were reported late yesterday evening, February 14, and have been passed on to the Food Standards Agency.

"The county council's catering service submitted a range of beef products from its suppliers to be analysed by Lancashire County Scientific Services, in accordance with Food Standards Agency guidelines."

Councillor Susie Charles, cabinet member for children and schools, said: "We share the concerns people have about what is clearly a major problem in food supplies across the UK and Europe.

"Because of those concerns we decided to seek extra assurance that our external suppliers were not providing any products containing horsemeat DNA, and one of the products has returned a positive result.

"Relatively few schools in Lancashire use this particular product but our priority is to provide absolute assurance that meals contain what the label says – having discovered this one doesn't, we have no hesitation in removing it from menus.

"This does not appear to be a food safety issue but I've no doubt parents will agree we need to take a very firm line with suppliers and it is a credit to our officers that we have been able to quickly identify the problem and take the product off the menus."

Lancashire Trading Standards is one of 28 services across the country taking part in the FSA's testing programme for horse DNA.