Media playback is unsupported on your device Media caption Environment Secretary Owen Paterson attended emergency talks in Brussels

Prime Minister David Cameron has said the "full intervention of the law" should be brought to bear on those who have passed off horsemeat as beef.

His comments came after two UK meat firms were raided by the Food Standards Agency and police.

The European Commission has now recommended EU states conduct random DNA tests on processed beef products.

It was among a list of demands made at an EU crisis meeting in Brussels, which were welcomed by the UK government.

The commission also said equine DNA horsemeat across the EU should be randomly tested for the veterinary drug phenylbutazone (bute), which is not allowed to enter the food chain.

The tests, by the food standard authorities of each member state, should begin on 1 March, and continue for three months. However, they should report back after 30 days, it said.

Environment Secretary Owen Paterson had earlier called for DNA testing of processed meat across the EU.

"I think we have a problem that affects all countries across Europe and we need results fast," he said ahead of the meeting.

"Nobody had a clue" until recently that beef products had been adulterated, he said, adding it had initially appeared to involve "very small amounts" of horsemeat.

But he said: "What changed the whole thing on to a completely different plane was the revelation from Luxembourg of significant amounts of horse. That has changed the whole argument."

'True picture'

Earlier, Mr Cameron had defended the government's response to the growing scandal.

"We've agreed a tougher inspection regime, we've asked hospitals and schools and prisons to check with their suppliers that they are testing their products... if there has been criminal activity then there should be the full intervention of the law," he told MPs during Prime Minister's Questions.

Safety issues Experts say horsemeat is as safe to eat as beef

The Food Standards Agency (FSA) has ordered food businesses to check for horsemeat in all processed beef products, such as burgers, meatballs and lasagne. The first set of results are expected on Friday

There is concern that some horses are given a drug called bute (phenylbutazone) which can be dangerous to humans

In rare cases it causes a serious blood disorder known as aplastic anaemia, where the body does not make enough new blood cells

Animals treated with phenylbutazone are not allowed to enter the food chain for this reason

The Food Standards Agency has ordered Findus to test its beef lasagne that contains horsemeat for bute

Results are expected imminently

He said there was no evidence that products on the shelves of British shops were unsafe to eat.

In Brussels, Mr Paterson met with counterparts from the Irish Republic, France, Romania, Luxembourg, Sweden and Poland.

Meanwhile, the prime minister of Romania, where two abattoirs are alleged to have sold horsemeat purported to be beef to European food companies, has said that the scandal is a continent-wide problem.

Victor Ponta told BBC Newsnight: "This is a very serious European crisis, it's not Romanian or British or French, it's a European crisis because it affects the absolute right of European customers to trust the food, to trust products and know exactly what kind of food it is and where it comes from."

Referring to the allegations, he added: "We have checked all data we had up to now regarding the plants and the way the meat has been processed, and up to now haven't found any irregularities."

The horsemeat scandal began last month when Irish authorities discovered horsemeat in some burgers stocked by a number of UK supermarket chains.

Horsemeat has also been found in branded and supermarket-own ready meals, including lasagne and spaghetti bolognese. Some Findus frozen beef in lasagne, made by a French food processing company, was found to be up to 100% horsemeat.

The FSA in the UK has ordered food businesses to carry out tests on all processed beef products and the first results are expected on Friday. They are testing for the presence of horsemeat and pork.

'Contradictory results'

More than 12 food firms met Food Minister David Heath on Wednesday and they reassured him their tests would be completed by Friday.

Shadow environment secretary Mary Creagh said she wanted Mr Paterson to come back from Brussels having secured a European-wide testing regime because "it's clear this is not just a UK or an Irish problem".

The FSA also ordered an audit of all horse-producing abattoirs in the UK. There are five abattoirs operating that are licensed to slaughter horses in the UK and last year 8,500 carcasses were exported to Italy, France and Belgium. It is not illegal to sell correctly labelled horsemeat in the UK but there is no demand for it.

Media playback is unsupported on your device Media caption Dafydd Raw-Rees, Farmbox Meats: "No cross contamination"

FSA director of operations Andrew Rhodes told the BBC the raids on Tuesday had been a result of those investigations, and his officers had returned to the premises on Wednesday morning. The FSA suspended operations at both raided premises and seized paperwork.

The raided premises were Peter Boddy Licensed Slaughterhouse, in Todmorden, West Yorkshire, and Farmbox Meats Ltd, of Llandre near Aberystwyth.

Mr Boddy said he was co-operating with the FSA and officials were "welcome to visit" his premises whenever they wanted.

Dafydd Raw Rees, of Farmbox Meats, said the firm was licensed to deal with horses and it had been cutting horsemeat from the Republic of Ireland, for export to Belgium, for the last three weeks.

The FSA has stressed that horsemeat does not pose a health risk to the public.

However, there have been concerns that if unregulated horsemeat is substituted for beef it could expose people to phenylbutazone.

The government has confirmed there were nine positive tests for bute in horsemeat slaughtered in the UK last year. In the last four years, a total of 15 positive bute samples have been taken from horsemeat in abattoirs.

'Trace of horse'

In the UK, wholesaler Makro became the latest firm to announce that a "trace of horse" had been found in a brand of beefburgers. The firm removed all frozen beefburgers from sale in January in order to test them.

"One brand - Unger beefburgers 48/4oz supplied by Silvercrest Foods - did contain a trace of horse. We no longer sell the Unger product," a spokesman said.

And in a separate development, a Glasgow firm has been named as the source of Waitrose own-brand Essential frozen beef meatballs which may contain pork.

Waitrose said it had checked 40 meat products in light of the horsemeat scandal and tests on the meatballs were found to possibly contain pork, which were produced at the ABP Foods-owned Freshlink factory.

A spokeswoman for ABP said: "Freshlink has carried out over 450 DNA tests during the last two-and-a-half years. All our test results have been confirmed as negative for non-declared species."