Three suspected criminal gang members have been arrested during an early-morning raid at addresses across Camden as part of the police’s on-going battle against courier fraud.

Some 30 officers took part in the swoop at six addresses last week, knocking down doors, seizing evidence and detaining three young men aged between 17 and 26.

Evidence bags full of high-value mobile phones, laptops and sim-cards were also seized at the addresses in the Mornington Crescent and Euston areas.

The arrests followed months of evidence gathering as part of Operation Easton – the attempted crackdown on courier frauds by Camden Police.

The relatively new kind of scam, which reached unprecedented levels earlier this year, typically involves elderly people being called by conmen pretending to be police officers or their bank.

Victims are encouraged to provide bank details such as account and pin numbers before being told to give their card to a “courier” sent round to their house – typically an unaware taxi driver.

On receipt of the card, the criminal gangs will then withdraw large sums of cash out of the victim’s account, go on spending sprees or, as happened in one case, buy a luxury holiday to Miami.

It’s a practice that has left Londoners swindled out of over £3million since 2011.

Residents in Camden have been the hardest hit in London with 232 reported courier fraud cases in 2012 – the highest in the capital.

But police have seen a dramatic reduction since setting up a specialist unit in conjunction with the London Fraud Squad last year and there have been just 59 cases between January and September.

Det Sgt Nick Giles, from Camden Police, said success is a case of “blowing open” organised criminal networks.

“These groups are often highly organised and use sophisticated methods. They ask victims to type pin numbers into their phone, then use a special app to determine the tones.

“They even play tape recordings to simulate an office environment when ringing. It all makes it very believable for the victims.

“But we have made real progress catching them. You’ll often get one break that will allow you to get into the organised criminal network and it blows it all open.

“It’s about being meticulous to find that one lead which will then lead to many other arrests.”

While the police appear to be making headway into the spate of frauds, the crimes have left in their wake numerous victims suffering long-term psychological trauma.

Those targeted are often elderly and vulnerable, with some suffering dementia or amnesia.

So terrible is the effect on their lives that a strong stigma has developed amongst other criminal elements against those caught committing the crime.

Det Sgt Will Cole, of Camden Police, said he had even seen fraudsters “beg” officers to keep their crimes secret from other prisoners.

“In terms of police and interestingly also in terms of other criminals, they really are considered the lowest of the low,” he says.

“The stigma attached is so great they’ll beg you not to tell other prisoners why they’re in prison.

“Other criminals look very dimly on it as their crimes are considered so unpleasant.”

The police claim the progress made should mean offenders no longer see Camden residents as easy targets and will now look elsewhere to carry out their lucrative scams.

They say they have been asked by other police forces around the country how they can prevent their own spate of courier frauds.