China's top price regulator will soon launch "large-scale and systematic" anti-trust investigations into drug companies, both foreign and domestic, after it recently summoned them to collect data and information, a source close to the regulator said on Friday.

The National Development and Reform Commission may require more drug companies to provide information after Pfizer, a US pharmaceutical company, and a number of distribution companies and medical device manufacturers were summoned, according to the source, who requested anonymity due to lack of authorization to speak on the matter.

The commission, which is in charge of China's anti-trust affairs, is collecting evidence to see whether these companies might have violated regulations regarding competition, according to the source. But this does not mean these companies have violated the law, the source said.