BEIJING, China (AP) — Chinese police have arrested 15,000 people on suspicion of cybercrimes as the government tightens its control over the Internet, the Ministry of Public Security said Tuesday.

Police throughout the country have investigated more than 7,400 cases of possible cybercrimes, including hacking, online fraud and illegal sale of personal information, resulting in 15,000 arrests, the ministry said. It did not say when the arrests were made.

Authorities launched a six-month special operation to clean the Internet in July, but some of the cases date back as far as December.

Beijing considers the Internet to be a virtual territory that must be ruled by laws and regulations.

Recently, authorities detained a man for exaggerating the death toll from blasts last week in the port city of Tianjin. Police also detained a woman who falsely claimed her father was killed in the explosions and sought donations from the public. At least 114 people were killed in the disaster, which is one of the worst industrial accidents in recent years in China.

The ministry said the special operation has snared suspects who hacked into websites of companies, banks and government agencies. Some obtained personal information illegally, some altered web information or uploaded content related to online gambling, and some used the Internet to defraud others, it said.

Beijing also prosecutes improper online speech, although the ministry’s announcement did not list cases involving that.

Pu Zhiqiang, a prominent rights defence lawyer, has been indicted on charges of fanning ethnic hatred and provoking trouble. The charges stem from online comments that questioned China’s ethnic policies and practices and mocked political figures.