The horse meat came from 200 slaughtered animals originating in equestrian riding centres, pharmaceutical laboratories and private owners in France and entered the food chain at the height of an international scandal in 2013.

Included in the fraud was meat from dozens of horses that were used by a French pharmaceutical firm, Sanofi Pasteur, to develop serums against rabies and other diseases.

The meat, unfit for human consumption and accompanied by fake documents labelling it as beef, was delivered to five Dutch companies via Belgium between January and October last year.

The latest fraud involving 200 horse carcases was only discovered on 27 Dec 2013 after an investigation by officials from [Holland's] Food and Consumer Product Safety Authority (NVWA).

It followed the arrest last month of 21 cattle traders, butchers and veterinarians in France on suspicion of illegally selling the horse meat.

Some of the meat has been traced but most has almost certainly been eaten by consumers although it posed little danger to human health, said the Dutch food inspectors.

"The microbiological risks are very small, because the slaughter took place in approved EU slaughterhouses," said a statement.

The scandal first emerged exactly one year ago when horse DNA was found in frozen burgers sold in Irish and British supermarkets after entering the food chain via a highly complicated international fraud involving traders and abattoirs from Romania to the Belgium and the Netherlands.

British MPs have warned that lessons remain to be learned one year after the horsemeat scandal broke on 14 Jan 2013.

"Retailers still need to work on smaller supply chains. By buying local we can more likely trace all sources of our food," said Anne McIntosh MP, the chairwoman of the cross-party environment, food and rural affairs committee.