Media playback is unsupported on your device Media caption Sainsbury's chief executive Justin King: Supermarkets "not out of woods" on horsemeat

The horsemeat scandal is not "the tip of an iceberg", the chief executive of a major UK supermarket chain has said.

Justin King, of Sainsbury's, made the comments after initial results of tests on processed beef revealed horsemeat was found in just over 1% of samples.

The Food Standards Agency said that after 2,501 fresh tests no new products had been identified as containing more than 1% horsemeat.

Three men arrested during the horsemeat adulteration probe have been bailed.

The men, two aged 64 and 42 from the Aberystwyth area and one aged 63 from West Yorkshire, were arrested on 14 February on suspicion of fraud.

Dyfed-Powys Police and FSA officials are continuing inquiries at Farmbox Meats near Aberystwyth.

'Essential step'

FSA chief executive Catherine Brown said she remained "confident" that testing was the right way to address the issue.

What is meat? To be labelled as meat, a product needs to conform to a European Commission standard.

Meat is restricted to skeletal muscle with naturally included fat and connective tissue.

Any fat or connective tissue in excess of the limits set out cannot be counted towards the meat content.

The maximum limits are:

Pork: 30% fat, 25% connective tissue.

Birds and rabbits: 15% fat, 10% connective tissue

All other red meat (including beef): 25% fat, 25% connective issue.

Mechanically recovered meat cannot be counted towards the meat content.

The legally required minimum meat that must be included in beefburgers in the UK is 62%, or 47% for economy beefburgers Source: Defra What is the Food Standards Agency? Horsemeat scandal: Test results

"It is industry's responsibility to get this right - not the government's - and we consider that a comprehensive testing programme at all points of the supply chain and in all sectors is an essential step in addressing this issue.

"And as this programme of testing and publishing results continues, and as action is taken to tackle this issue in supply chains across Europe, we will reach the point where we can say with confidence that horse meat is no longer illegally entering the UK food chain."

Meanwhile Tesco chief executive Philip Clarke has sent a message to customers: "Since we became aware that a small number of Tesco processed meat products have been contaminated with horsemeat, we have been working flat out to get to the bottom of the issue.

"While tests continue, today I want to make a clear promise to customers and to tell you about the rigorous processes we have put in place to prevent this situation happening again."

He said that from Saturday if a product tested positive and was withdrawn from sale, Tesco would provide customers with a "better alternative" for the same cost.

'Encouraging signs'

Mr King rejected Downing Street's criticism that supermarkets had been slow to respond to the scandal.

On Friday he told BBC Two's Newsnight programme: "I don't think it's the tip of an iceberg. I think there are some encouraging signs from today's tests that we are starting to get to the bottom of this particular issue."

However, he went on to warn that nobody can say they are "out of the woods" yet.

"There is a long way to go before we can truly say we understand how this came about and therefore what we have to do differently going forward," said Mr King.

No meat at Sainsbury's has so far been shown to contain horsemeat.

Labour leader Ed Miliband said the government had been "slow off the mark" in handling the scandal and clearer guidance should have been offered, including to schools and hospitals.

Media playback is unsupported on your device Media caption Steven Poole: Low prices are important to people

"I think the retailers do have a responsibility but I also think the government has not been as sure-footed as it should have been in its handling of it," he said.

Catering giant Compass Group and Whitbread, one of Britain's largest hotel chains, have found horse DNA in products sold as beef, it emerged on Friday.

Horse DNA has also been found in cottage pies supplied to 47 schools in Lancashire - they have been withdrawn.

Anne Bull, chair of the Local Authority Caterers' Association, told the BBC: "We have got stringent and robust procurement procedures in place for local authority-maintained schools.

"Lancashire have got some minute traces of equine DNA in their cottage pies. These have been withdrawn with immediate effect so there is no risk to the children at the moment," she added.

She said school caterers take "on good faith" the meat they are supplied and expect "it is what it says on the tin".

Ms Bull said the next 10 days were likely to be "critical" as test results come through from the FSA.