UK supermarkets have hit back at government criticism that they “remained silent” over the horse meat scandal as early test results of processed meals give grocers’ products the all-clear.

The results of two thirds of the tests have given grocers the all clear, with the Food Standards Agency already notified on the five products which have been found to contain horse meat, which have already been withdrawn from sale.

Iceland said that all of its own brand beef products were free of horse meat while results so far from the Food Standards Agency tests have given The Co-op, Morrisons, Tesco and Sainsburys the all-clear.

Meanwhile, supermarkets groups have said that they have been “working around the clock” to resolve the matter hitting back at Government criticism that they had questions to answer on the scandal.

A public letter issued today, signed by Tesco boss Philip Clarke, Asda chief executive Andy Clarke, Sainsburys chief Justin King and Morrisons’ Dalton Philips, said: “We can’t accept a situation where the trust customers place in us is being compromised by fraudulent activity or even as alleged, an international criminal conspiracy.

“We will do whatever it takes to restore public confidence in the food they buy and eat.”

Earlier, sources at Downing Street had said: “It isn’t acceptable for retailers to remain silent while customers have been misled about the content of the food they have been buying.”

Morrisons also hit back on its Twitter account. It said: “Contrary to what No10 is saying, we haven’t all been silent.”