BEIJING, Aug. 25 -- Beijing police have busted a gang illegally selling resident permits for the city, the municipal public security bureau confirmed on Monday.

The 16 suspects all work for large state-owned or high-tech enterprises that are granted a certain number of the permits, or "hukou," for new employees who have recently graduated from university.

They made more than three million yuan (487,590 U.S. dollars) selling the permits to about 80 graduates who did not join the companies in question, police say.

The procurator has ratified the arrest of 13 of them on suspicion of buying and selling official documents, and abuse of power.

In early July, police found an article online in which a graduate claimed to have got a Beijing hukou by paying 300,000 yuan to a man surnamed Tian.

From mid-July, they caught Tian, the manager of an information technology company, and 15 other suspects. Each hukou was sold for between tens of thousands of yuan and about 300,000 yuan, according to the police.

"We formed a connection network by sharing messages and handling the hukou-related affairs," said a suspect surnamed Zhang, a 41-year-old female department manager of an Internet technology company which was able to acquire five or six permits for fresh graduates.

The public security bureau said police investigation found Tian marketed the scam online and sent applicants' details to his accomplices who would secure the permits.

Beijing had a permanent population of 21.14 million people at the end of last year. More than 8.02 million of them, or 38 percent of the total, had no Beijing hukou, according to the Beijing Municipal Statistics Bureau.