China ordered internet service providers to participate in a drill Thursday for taking down websites deemed "harmful" by the Beijing government.

The three-hour drill, billed as an opportunity for participants to test their "emergency reponse" skills, was viewed by critics as the latest attempt by China to tighten censor controls on Internet data centers and cloud companies, which host website servers, Reuters reported.

According to a document attributed to cyber police, China’s Ministry of Public Security called for the drill to “tackle the problem of smaller websites illegally disseminating harmful information,” the news agency reported.

China has been tightening its grip on the internet in recent years, especially since President Xi Jinping took office in 2012. Most recently, Jinping has increased data surveillance and censorship rules ahead of a key Chinese Communist Party meeting in the fall, the 19th Party Congress, the New York Times reported.

Recent attempts to crack down on virtual private networks, which are used to bypass China’s firewall, have resulted in major changes like Apple removing VPN apps from its app store last week.

Apple CEO Tim Cook recently defended the company's move, saying it was simply complying with Chinese laws. But critics accused Apple of appeasing the government of a nation that accounted for about $8 billion of its revenue in the fiscal third quarter, as Fox News reported.