MPs have signalled frustration at the pace of the investigation into the horse meat scandal in the UK with no one prosecuted exactly six months since the crisis first erupted.

Authorities in the UK and Ireland are yet to root out the “complex network of companies” responsible for the large-scale fraud, according to Food Contamination, a new report from the Environment, Food and Rural Affairs Committee (EFRA).

Major UK grocers including Tesco, Asda and Lidl were found to have stocked products containing horse meat and have since conducted internal investigations, changed suppliers and introduced new testing measures on meat.

However, EFRA committee chair MP Anne McIntosh said the lack of prosecutions had caused “dismay” in Government and is preventing a return of consumer confidence.

She said: “The evidence suggests a complex network of companies trading in and mislabelling beef or beef products which is fraudulent and illegal.

“We are dismayed at the slow pace of investigations and seek assurances that prosecutions will be mounted where there is evidence of fraud or illegality.”

McIntosh called for the Food Standards Authority (FSA) to become “a more efficient and effective regulator”. She demanded better communication between the FSA and its EU counterparts, more trained food analysts, and for major grocers to pay for regular DNA testing of meat products and ingredients.