China arrested four civilians working at a defense firm on claims of selling military secrets to foreign intelligence agencies, state media reported on Wednesday, the latest in a string of espionage-related arrests.

The defense workers are suspected of divulging secrets about the testing, production and use of new and high-tech weapons, China Radio International said in an online report, citing the state security agency in the southwestern province of Sichuan.

They also sought out defense technicians to introduce to "overseas spies," the report added.

The four did not know each other though they worked for the same company, the report said. It did not specify which foreign spy agencies the four had given information to, but cited local media reports as saying agents had approached them online via social media.

In November, a man was arrested in the coastal city of Qingdao for taking photos of an aircraft carrier base and selling them to a foreigner.

China's state secrets law is notoriously broad, covering everything from industry data to the exact birth dates of state leaders. Information can also be labeled a state secret retroactively.

In severe cases, the theft of state secrets is punishable with life in prison or the death penalty.