Supermarket giant Tesco has placed full-page adverts in a number of national newspapers apologising to customers for selling beef burgers containing horse meat.
It has also promised to refund customers who bought the contaminated products, and said sorry for the "unacceptable'" situation.
The apology came as a food expert claimed horse meat could have been in beef burgers for years, but remained undetected because of insufficient food regulation.
The UK's food watchdog, the Food Standards Agency (FSA), is also considering taking legal action against companies at the centre of the scandal.
Tesco promised refunds to customers who had bought the contaminated products, which it identified as Tesco Everyday Value 8 x Frozen Beef Burgers (397g), Tesco 4 x Frozen Beef Quarter Pounders (454g), and a branded product, Flamehouse Frozen Chargrilled Quarter Pounders.
In the advertisement, entitled "We apologise'', Tesco says: "While the FSAI (Food Safety Authority of Ireland) has said that the products pose no risk to public health, we appreciate that, like us, our customers will find this absolutely unacceptable.''
It continues: "We have immediately withdrawn from sale all products from the supplier in question, from all our stores and online... We and our supplier have let you down and we apologise.''
The advert concludes: "So here's our promise. We will find out exactly what happened and, when we do, we'll come back and tell you.
"And we will work harder than ever with all our suppliers to make sure this never happens again.''
The apology came as a reported £300 million was wiped off Tesco's stock market value.
Experts have today warned that the popular animals could end up on the plates of unsuspecting diners.
At least 200 pure-breed New Forest ponies were up for auction last year at Beaulieu Road Sales, with many destined for abattoirs because the "bottom has fallen out of the market".
As it was revealed that scientific tests found horse meat within burgers sold by supermarkets such as Tesco, Lidl and Aldi, New Forest Verderer Colin Draper told the Daily Echo that unwanted ponies were being snapped up by English abattoirs for as little as £10.
They then sell them on to the French – where the rogue burger meat is believed to have originated.
He said: “It may well be that people are eating New Forest ponies.
“It is not something we promote.
It is a last resort but there are definitely a few that get taken to the slaughterhouse.
“The bottom has fallen out of the market since the economic slump because keeping them is an expensive hobby.”
Strict rules Mr Draper said strict live animal export rules meant horses were now taken to two British abattoirs, in Cheshire and Bristol.
Dionis McNair, a Verderer and a member of the New Forest Pony Breeders and Cattle Society, blamed the oversupply on over-breeding and changing fashion in horses.
She said: “It is a very worrying situation. We would all like the ponies to be used as riding ponies.”
To alleviate the problem, the Verderers, who represent the interests of animal owners in the Forest, have reduced the number of stallions from 40 to ten in the past four years in a bid to reduce the surplus.
Lee Hackett, from the British Horse Society, said the ponies may be attractive to abattoirs because they have less medicine in them then more domesticated horses.
He said: “It means they are more likely to legally enter the food chain. I think the problem is that there are too many horses and there are not enough nice homes for them. Supply has outstripped demand.”
Horse meat accounted for about 29 per cent of the meat content in one burger sample from Tesco, according to the study carried out by the Food Safety Authority of Ireland (FSAI).
Professor Alan Reilly, chief executive of the FSAI, said there was no health risk but also no reasonable explanation for horse meat to be found.
Tesco, Lidl and Aldi have told food safety chiefs they have removed all implicated products from their shelves.