An official with knowledge of the investigation said the group allegedly sold the trade secrets to Jiangyin Jianghua Microelectronics Materials, a tech company based in China's eastern Jiangsu province, pocketing $1.3 million.
"The technology involved in the case has an estimated market value of 100 million euros ($114 million) although the suspects were caught before they could sell the most confidential information," the official, who asked not to be named, told AFP.
The CIB did not provide a breakdown of how many suspects were working for BASF at the time of the arrests but they said they included "high ranking" officials including at least one at factory director level.
In a statement on its local website, BASF said one current local employee was under investigation.
"We have taken immediate steps to support the investigation led by local law enforcement officials and protect the relevant information," the company said.
China has denied the allegations and has taken steps to improve IP protections in recent years, including establishing specialised courts to handle matters including patent disputes, copyright and trademark infringement.
Employees at Taiwanese companies have previously faced allegations of trade theft benefiting China.
In October 2018, the US restricted sales of crucial technology to China's state-owned chipmaker Fujian Jinhua, accusing it of stealing trade secrets from US-based semiconductor giant Micron with the help of officials from
Taiwan's United Microelectronics Corporation (UMC).
A year earlier, five former employees of Taiwan's local Micron subsidiary were charged with passing trade secrets to China.