A gang of fraudsters have been jailed for between 21 and 64 months for stealing bank card details potentially worth up to £16m from more than 60,000 people in the UK and abroad.

Three men and a woman appeared at the Old Bailey in London for sentencing after pleading guilty to a string of fraud offences after police uncovered what they described as a "fraudster's utopia" in Harrow, Middlesex.

The prosecutor Catherine Pattison said the defendants – who were living at addresses in the area – were responsible for "a large-scale, highly sophisticated, well-executed ATM and counterfeit fraud".

The criminal operation was stopped in December last year when police seized an array of gadgets including cards traps, cloned cards and spy cameras in raids.

The gang from Romania were involved in three stages of fraud – stealing bank card data from cash machines, downloading it on to a computer and then copying the details on to counterfeit plastic cards, Pattison said.

In all, 953 bank accounts had been compromised and a total of £161,607.47 was taken, although the potential loss was far greater, she said.

Money was then transferred overseas to Panama, Romania, Italy and Colombia using MoneyGram and Western Union, the court was told.

The prosecutor said Florin Silaghi and Vasile Pop were the key players in the conspiracy, and Ovidiu Metac and his partner Adriana Turc had lesser roles.

They all pleaded guilty at earlier hearings to conspiracy to defraud between 1 January 2012 and 11 December 2013 and various other related offences.

Silaghi was jailed for 64 months, Pop for 61 months, Turc for 21 months and Metac for 43 months.

Jailing the four on Thursday, the recorder Douglas Day QC said: "Electronic card fraud is one of the scourges of the technological age both nationally and internationally. It causes significant loss to the banks and distress and inconvenience to the cardholders whose cards have been compromised."

Silaghi, 30, of Kenton Lane, Harrow, also admitted possessing criminal property relating to bank details, making a scanning device and possession of an identity document with improper intention.

Metac, 25, of Welldon Crescent, Harrow, pleaded guilty to having bank details on a computer, having counterfeit plastic cards, cash machine card slots and a fake photo identity card.

Turc, 27, also of Welldon Crescent, pleaded guilty to having bank account details on a computer and two counts relating to the transfer or acquisition of money.

Pop, 30, of Kenmore Road, Harrow, pleaded guilty to two counts of the transfer or acquisition of money.

Following the sentencing, police said 36,000 of the more than 60,000 card details found belonged to people in the UK.

Many of the cards found had the number of the stolen pin written in black marker pen on the back for easy use by the criminals, said a spokesman for the dedicated cheque and plastic crime unit (DCPCU), a specialist police unit.

The cards recovered had a street value of £16m based on the amount stolen on average from a compromised card, they said.

As officers investigated the case, evidence of a method never seen before in the UK to steal card details came to light – spy cameras fitted to the side panel of cash machines, rather than the top panel.

This method allowed fraudsters a better view of people's pin numbers when the keypad is only partially covered by the customer's hand.

DI Sarah Ward, who led the investigation for the DCPCU, said: "We are delighted that with these arrests and convictions we have been able to completely dismantle a criminal organisation that was stealing millions from people's bank accounts.

"The premises we raided really were a fraudster's utopia, with a dizzying array of machines and gadgets designed to commit serious fraud.

"These convictions send out a strong message to would-be fraudsters but there is also a word of caution for customers – always cover your pin closely with your hand when using a cash machine to beat the criminals."

Virgil Spiridon, director of the organised crime department at the Romanian national police, added: "Close co-operation between the DCPCU and our own officers played a key part in successfully securing these convictions.

"It was an excellent example of law enforcement agencies from different countries working together to ensure fraudsters' activities are brought to a halt and their crimes are punished."

Since the DCPCU was set up in April 2002, it has saved around £450m by clamping down on fraud activity.