Horsemeat was unknowingly sold by a host of UK supermarket chains after a gang secretly mixed it with beef, a court has heard.

The three men involved in the scam then falsified documents, a jury was told, as the chain of events that led to the horsemeat scandal was laid bare for the first time in the trial of businessman Andronicos Sideras.

The 55-year-old, who is said to have played a “key role” in the scandal, is accused of mixing horsemeat with beef and falsifying documents to sell it on as “100% beef” to manufacturers who made products for grocers including Tesco, Asda and the Co-op.

The 2012 scam was first uncovered in Ireland, where contamination was first identified before tests by the Food Standards Agency found horsemeat in products being sold in the UK.

It led to thousands of items being taken off shelves, while supermarkets’ reputations took a battering as they were forced to apologise to customers.

Sideras was arrested in 2013 alongside Ulrik Nielsen, the owner of Danish company FlexiFoods, and Alex Ostler-Beech.

The trio were charged with conspiracy to defraud, but while Nielsen and Ostler-Beech accepted the charges, Sideras denies the charge.

‘Dishonesty motivated by greed’

Jonathan Polnay, prosecuting, told jurors at Inner London Crown Court: “This case, stripped to its essentials, is actually very straightforward.

“It is about lying to people. It is about deceiving people to make money. Or to be more precise – for people to make more money.

“Like most if not all offences of dishonesty, it was motivated by greed.”

Sideras co-owned meat and sausage manufacturer Dinos & Sons, in Tottenham.

The court was told that FlexiFoods bought horsemeat and beef from suppliers across Europe and delivered it to Dinos & Sons.

The London-based firm is alleged to have charged up to four times more than usual in storage costs to mix the meats into “horsebeef.”

At the time, beef was selling for around €3 per kg, but horsemeat was around €1 per kg cheaper.

Polnay said: “Whilst at – Dinos  and this is the heart of our – case the horsemeat and the beef would be mixed together into a single load.

“Dinos would create false paperwork and labels to make it look like all the meat being supplied was beef.”

Polnay alleged that the “key role” of mixing the meat and fixing the documents to make them look genuine was undertaken by Sideras.

The trial of Sideras continues and is expected to last four weeks.