Bosses at Bradford-based Morrisons supermarkets have ordered urgent checks to ensure none of its processed meat products are contaminated with horse meat.

The move follows revelations that beefburgers on sale in the UK and Ireland by rivals Tesco, Iceland and other stores contained up to nearly 30 per cent horse meat.

A Morrisons spokesman said the company was “double checking” fresh and frozen meat products for any traces of contamination, but stressed it sourced most of its meat direct from farmers and processed more of its own food than competitors.

He said: “In the light of developments elsewhere we are double checking to ensure that our products are not contaminated. We know the source of most of our fresh meat which we buy direct from farmers.

“We’re also checking frozen meat products, including Morrisons own label and branded goods from third party suppliers.”

Food safety officials are working to trace the offending meat back to its source to find the cause of the contamination.

Professor Alan Reilly, chief executive of the Food Standards Agency, said there was no health risk, but also no reasonable explanation for horse meat to be found.

Tesco said all offending products had been removed from shelves and it was taking steps to ensure such contamination did not reoccur.

Iceland, Aldi and Lidl have also removed offending products and have started investigations into how the contamination happened.

The meat came from North Yorkshire processor Dalepak Hambleton and Liffey Meats and Silvercrest Foods in the Republic of ireland. They are both investigating two continental European third-party suppliers and stressed they had never bought or traded in horse products.

The burgers had been on sale in Tesco and Iceland in the UK and the Republic of Ireland, where they were sold by Dunnes Stores, Lidl and Aldi.

A total of 27 burger products were analysed, with ten showing traces of horse DNA and 23 containing pig DNA.

Horse meat accounted for around 29 per cent of the meat content in one sample from Tesco, which had two frozen beefburger products sold in both the UK and Ireland contaminated with horse DNA. In addition, 31 beef meal products, including cottage pie, beef curry pie and lasagne, were analysed, of which 21 tested positive for pig DNA.

Tim Smith, Tesco’s group technical director, said the company was working with UK and irish authorities as well as with the supplier concerned to understand how the contamination occurred and to prevent repetition.