The Metropolitan Police has warned it is working to track down 11,000 customers of a gang that specialised in providing fake IDs.
The people behind the online enterprise, Confidential Access (CA), sold fake IDs, documents and tips on how to commit fraud to their clients.
CA's leaders ran it from Alicante, Spain, while UK employees monitored the website and produced false documents.
Six gang members were sentenced on Friday at Southwark Crown Court.
Police conducted a two-and-a-half year investigation which led to four of the men being jailed.
'Credit histories ruined'
Many of CA's "authentic-looking documents" were bundled together and sold as full credit profiles, including wage slips, credit history print-outs and a postal address.
This made it possible for CA customers to defraud companies out of thousands of pounds, the Met said.
Det Insp Tim Dowdeswell said some people's credit histories had been ruined by those involved with CA and that the operation had netted millions of pounds for the criminals.
He added: "We have already brought many of their students in crime to court and will continue to work with other police forces and partners to bring those people who bought and used these identities in their own frauds to justice."
One of CA's top-end products was called the platinum profile.
It cost £5,500 and came complete with instructions on how to commit identity fraud.
Advice and coaching
For £2,000, CA also sold the 100% creditmaster profile, which was exclusive to so-called VIP members of the website, police revealed.
But if the customer successfully committed fraud with it, CA would ask for 50% of the proceeds from the first fraud or threaten to wreck the credit profile.
Web chat forums played a key role, providing clients with information, advice and coaching them on how to use the profiles, said the Metropolitan Police.
Some of the forums were free but others came at a cost.
A monthly subscription fee bought members access to forums where they could discuss how to use the identity documents to break the law and seek other tips and advice.
Access to the forums was graded and some were open only to those members who spent a specific amount of money and had gained a certain level of trust, the Met said.
People in the top tier were classed as VIP members and had access to a forum called "The Black Marketplace".
This is where serious incriminating topics were discussed and hidden from the general public and non-VIP members, the Met added.
Nautical terms were used to distinguish the varying levels of trust within the forums.
All new, paying members would begin as deckhands and as they gained trust would climb the rank ladder from skylarker to shore patrol, up to the ship's surgeon, who was in charge.
Analysis of servers, which had been seized from Hong Kong, led to a breakthrough by officers when they cracked the encryption codes, revealing the evidence they needed to prosecute.
The operation was run by Jason Place and Barry Sales.
Place, 42, of Aurora Court, Romulus Road, Gravesend, Kent, was jailed for six years and nine months for conspiracy to defraud.
The Crown Prosecution Service took no action against Sales as he is terminally ill.
Mark Powell-Richards, 59, a credit broker and antiques dealer of Nightingale Lane, Bickley, Kent, was jailed for two years and three months for conspiracy to defraud.
Allen Stringer, 57, of Coldwell Road, Crossgates, Leeds, was jailed for the same term and charge.
Jaipal Singh, 31, a telecoms company director, of Franchise Street, Wednesbury, West Midlands, was jailed for 18 months for conspiracy to defraud.
Michael Daly, 68, a former chauffeur of Stone Court, High Street, Erith, Kent, was sentenced to 12 months, suspended for two years, and ordered to carry out 250 hours of unpaid community service for conspiracy to defraud.
Student Arun Thear, 22, of Walsall Road, West Bromwich, West Midlands, was sentenced to six months, suspended for two years, and ordered to carry out 150 hours of unpaid community service for forgery, contrary to section 1 of the Forgery and Counterfeiting Act 1981.
All six had pleaded guilty at earlier hearings.