Police investigating allegations that horsemeat was mislabelled as beef have arrested three men on suspicion of offences under the Fraud Act.
Two men, aged 64 and 42, were held at Farmbox Meats Ltd, near Aberystwyth, and a 63-year-old was arrested at Peter Boddy Licensed Slaughterhouse, in Todmorden, West Yorkshire.
Both firms have denied any wrongdoing.
An Asda Bolognese sauce has become the first fresh beef product withdrawn, over fears it contains horse DNA.
The supermarket giant withdrew its 500g own-label Beef Bolognese sauce, saying a preliminary test result suggested the presence of horse DNA.
Concerns about horsemeat in processed beef products first came to light on 15 January and until now recalls by supermarkets have involved frozen products.
As a precaution, Asda is also withdrawing three other beef-based own-label products from the same supplier, Bristol-based Greencore: its 600g Beef Broth Soup; 500g Meat Feast Pasta Sauce and 400g Chilli Con Carne Soup.
In a statement, Greencore said the sauce contained meat supplied by the ABP Food Group's Nenagh plant in County Tipperary, Ireland.
ABP owns meat processor Silvercrest which lost supply contracts with Tesco, Aldi and Co-operative supermarkets after horse and pig DNA was found in burgers it supplied. ABP says its meat is sourced from licensed EU suppliers and it has "never knowingly" used horsemeat.
The latest product withdrawal comes as the Food Standards Agency prepares to announce the results of industry test results on hundreds of processed beef products for the presence of horsemeat.
One of the men arrested at Farmbox Meats in Llandre is believed to be the firm's owner Dafydd Raw Rees, the BBC understands.
A Dyfed-Powys Police spokesman said the three people arrested were being detained at Aberystwyth Police Station and would be interviewed by its officers and FSA staff.
The Peter Boddy Licensed Slaughterhouse in West Yorkshire is reported to have supplied horse carcasses to the Aberystwyth plant, which were then allegedly sold on as beef for kebabs and burgers.
The Food Standards Agency (FSA) suspended operations at the meat firm near Aberystwyth and the slaughterhouse in West Yorkshire after raids at the premises on Tuesday.
It also seized meat found on the premises as well as paperwork, including customer lists from the two companies.
In other developments:
- The French processing company that supplied Findus sold meat labelled as beef despite knowing it could have been horsemeat, the French government has said. Spanghero had previously said it was a victim of its supplier but officials said it appeared the Romanian company had acted in good faith
- The European Union is urging member states to conduct random tests for horsemeat in processed beef products
- Horsemeat has been detected in frozen lasagne on sale in Germany and supermarkets have started removing the product from their shelves
- Beef has been removed from school meals across Staffordshire as a precautionary measure amid the horsemeat scandal
- A company that supplies frozen burgers to some Northern Ireland schools that were recalled as a precaution has said tests show they are clear of horse DNA
- In Wales, Conservative rural affairs spokeswoman Antoinette Sandbach has called for local authorities to test all meat entering the public sector food chain
- A meat processing factory in the Irish Republic, Rangeland Foods in County Monaghan, has withdrawn some batches of burger products which contained beef supplied from Poland - some of which were found to contain between 5-30% horsemeat
- A report from the Commons Environment, Food and Rural Affairs committee called for the FSA to have stronger powers to force meat producers to carry out testing
- Food minister David Heath said tests on Findus beef meals found to contain horsemeat were negative
The tests by Irish authorities last month found horsemeat in beefburgers made by firms in the Irish Republic and the UK and sold in supermarket chains including Tesco and Aldi.
A growing number of UK retailers later recalled processed beef products found to contain horsemeat. And last week the British unit of frozen foods giant Findus started to recall its beef lasagne on advice from its French supplier, Comigel, after tests showed concentrations of horsemeat.
The three arrests came after the FSA said on Thursday tests had found eight horses, killed in the UK, had tested positive for the equine painkiller phenylbutazone (bute) and that six may have entered the food chain in France.
But England's chief medical officer said the highest level detected posed "very little risk to human health".
The prime minister's spokesman said the UK was working closely with the French authorities to track the carcasses.
FSA rules, which came into force, this week mean all horsemeat in the UK will be tested for bute before it is allowed to be sold for food.
French food producer makes order
Comigel HQ in Metz, north-east France, asks its subsidiary, Tavola in Luxembourg, to make food products - including beef lasagne for Findus.
Factory orders meat
The Tavola factory orders the meat from Spanghero in the south of France.
Spanghero contacts a subcontractor in Cyprus to source the meat.
Subcontractor enlists trader
The Cypriot subcontractor in turn contacts a trader in the Netherlands.
Trader orders from Romania
The trader in the Netherlands places an order for meat with abattoirs in Romania.
Abattoirs send meat to France
The meat from the abattoirs travels to Spanghero in France. However, Romania rejects claims that it was responsible for wrongly describing the horsemeat from its abattoirs as beef. Horsemeat is always labelled as such, they say. The Romanian authorities claim records show orders had been for horse carcass - easily distinguishable from beef.
Meat used to make products
Spanghero sends the meat to the Comigel subsidiary’s factory in Luxembourg before the finished products are supplied to Findus and retailers across Europe, including the UK. The president of Comigel says the company was unaware the meat was coming from abroad.
Horsemeat found in Ireland and UK
Tests by Irish authorities have found equine DNA in beefburgers made by firms in the Irish Republic and the UK. Traces of horsemeat have also been found in stored meat at another plant in Ireland and one in Northern Ireland. In mainland Britain, police and officials probing alleged horsemeat mislabelling have carried out raids at a slaughterhouse in West Yorkshire and a meat firm near Aberystwyth. Three men were later arrested on suspicion of offences under the Fraud Act..