China’s market regulator on Thursday announced an investigation into alleged anti-competition practices by e-commerce giant Alibaba, as Beijing tightened control of an expanding Internet.

The investigation is first of its kind into a large Chinese tech company. It comes a month after authorities halted sister company Ant’s $37 billion initial public offering.

In a brief note, the State Administration for Market Regulation said that it is investigating Alibaba over its “choosing one from two” policy.

As part of this policy, merchants are forced to sell exclusively on Alibaba e-commerce platforms and skip rivals like JD.com.

“The State Administration of Market Supervision, based on reports, filed investigations into Alibaba Group Holdings Co., Ltd. for suspected monopolistic conduct such as ‘choose one out of two,'” the statement read.

Alibaba Group said in a statement that they have received notification from the State Administration for Market Regulation.

“Alibaba will actively cooperate with the regulators on the investigation,” the company said, adding that its “business operations remain normal.”

In a related development, Xinhua news agency said on Thursday that The People’s Bank of China, China Banking and Insurance Regulatory Commission, China Securities Regulatory Commission, and State Administration of Foreign Exchange will “interview Ant Group in the near future”.

The move is “to supervise and guide Ant Group to implement financial supervision and fair competition in accordance with the principles of marketisation and rule of law, and to protect the legitimate rights and interests of consumers, and regulate the operation and development of financial services”.

According to a Financial Times report, Ant in a statement confirmed of receiving a ‘meeting notice’ from regulators and would ‘seriously study and strictly comply with all regulatory requirements’.

The Chinese regulators have recently removed several apps, including banning thousands gaming apps on Apple App Store, in a wide-ranging “clean-up” of online content related to illegal activity, including obscenity, pornography, prostitution, violence, fraud or gambling.

With China cracking down on apps especially related to video games, Apple has warned Chinese app developers that thousands of more video games will be removed from App Store.

According to a report in The Wall Street Journal citing a memo, thousands of video games face removal as Beijing tightens control of Internet.