Four employees of a military defense firm in China’s Sichuan Province have been arrested on suspicion of selling confidential military information to foreign intelligence agencies.

Two suspects surnamed Wen and Wang are alleged to have been paid between 3,000 yuan ($480) and 4,000 yuan a month to provide information to a person identified only as “H,” who claimed to be a foreign journalist. Two other suspects were offered money to divulge classified state secrets.

Dubbed operation “Mine Sweep”,  the state security agency arrested four men on suspicion of selling information involving the research, testing, production and application of new high-tech weapons. They have also been accused of attempting to recruit other defense technicians into the spy network.

The four suspects reportedly worked at the same company, but did not know each other.

This isn’t the first time the internet has been used as a tool to sell Chinese secrets abroad. Last May, a Guangdong man was convicted of espionage and sentenced to ten years in prison for releasing state secrets he found on the Internet. The man accessed 13 highly classified documents ranked at the second-highest tier of secrecy in China, as well as 10 classified documents from the third tier.

According to a recent CCTV report, incidences of espionage are steadily increasing in China. The report quotes a counter-espionage officer from China’s Ministry of State Security who claims there are an increasing number of young Chinese men working for foreign spy agencies.