Image caption Farmbox Meats near Aberystwyth was one of two premises raided on Tuesday

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An Asda Bolognese sauce has become the first fresh beef product withdrawn, over fears it contains horse DNA.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.

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

The Food Standards Agency (FSA) has demanded 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 ordered Findus to test its beef lasagne that contains horsemeat for bute, but no traces were found Which products have been withdrawn?

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.

Painkiller detected

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 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.