Beijing police have rounded up 449 suspects in a crackdown on illegal professional training courses in the capital.

Victims of the fraud may have been conned out of more than 10 million yuan ($1.6 million) for training classes, fraudulently said to be set up by central government authorities, such as the Ministry of Human Resources and Social Security, Liu Chunjiang, a senior officer with the Fengtai district police bureau, said on Wednesday.

"On Monday, we went to their Beijing headquarters and took 525 people into custody," Liu said, adding that 449 are still being held.

Police also seized 161 computers and more than 500 fake documents, including certificates and invoices.

The suspects are accused of using a central government department's name to enroll students from across the country.

"They claimed to be running classes in preparation for professional licensing exams, and told applicants that they would be given official certificates authorized by the ministry," Liu said.

The training certificates were for a number of professions, including those in medicine and accountancy.

He said police began to receive public complaints about the fake classes in March and established a special investigative team of 700 officers.

The suspects' companies were based in the Fengtai district of the capital, but their training classes were geared to other cities, Liu said, which made it hard for victims to find the fraudsters.

The investigation spread to other provinces, including Henan, Hebei and Jiangsu, Liu said.

After a 20-day investigation, the police found the suspects, who had hidden their real identities by registering companies in other people's names, and had moved their workplace around different office buildings in the capital.

"They designed many fake professional training projects targeted at applicants who were keen to get certificates and the tuition fees were as high as 9,800 yuan per applicant," Liu said.

The swindlers even promised to pass applicant's qualification tests and give them certificates authorized by governmental departments if they paid 3,000 yuan more, Liu added.

"The fake training groups recruited their staff through the Internet. An employee could get salary of more than 10,000 yuan a month," he said, adding that the suspects had used the money to buy houses and luxury cars.

Tang Hongxin, a Beijing-based lawyer specializing in criminal cases, said the groups took advantage of the high demand for certificates in order to gain promotion or find better jobs.

"Beijing, as the capital, has many authoritative professional training projects and a reputation which may lure applicants from other cities," he said.

Qu Xinjiu, a criminal law professor from China University of Political Science and Law, said the principal suspects face sentences of life in prison in line with current Chinese Criminal Law.

"The suspects will get heavier punishments if they forged official seals and documents," he said. "The amount of their illegal income is also very huge, which will affect their penalty."