Authorities in China have shuttered the website and social media accounts of a prominent economics think tank amid a mounting assault on liberal academic voices.

The Unirule Institute of Economics in Beijing is the latest target of a government crackdown after the forced retirement of a professor who criticized Mao Zedong and sacking of a provincial official who called communist China's founder the "devil."

Liberal intellectuals and Chinese political observers are growing alarmed by the government crackdown, which overlaps with the rise of an increasingly cohesive and confident movement both on China's internet and its streets dedicated to defending Mao's reputation and his hardline legacy. Since President Xi Jinping took power in 2012, reformist magazines and websites have been shut while university professors and even the country's judiciary have been warned against spreading liberal Western values.

Mao Yushi, Unirule's founder who is not related to Mao Zedong, said Wednesday that representatives from the ruling Communist Party informed him last week that the website was shut down because it violated the law, but gave no details.

"It's a terrible thing, it existed for many years," Mao told The Associated Press. "I told (the officials) this is not the law, and they had no response because they won't answer these questions."

The Beijing branch of the Cyberspace Administration of China said this week it closed 17 websites, including that of Unirule, as part of a cleanup of websites providing unauthorized news and pornography.

Unirule and Mao Yushi are particularly reviled by China's increasingly vocal "leftists" who see their support of free-market economics as antithetical to Mao Zedong's revolutionary legacy and traditional Communist Party ideology. In recent weeks, Maoists have organized online campaigns and street demonstrations to target a succession of liberal academics, with the apparent support from Chinese authorities who typically break up most forms of unauthorized political activity.

The party's nationalistic Global Times tabloid, which reported Wednesday on the phenomenon of the growing Maoist movement, opined in a separate piece this week that Mao Yushi's silencing should serve as a lesson.

"Liberals absolutely must learn this lesson: openly being an oppositional speaker or denier will get you nowhere in China," said the op-ed, which was later removed from the paper's website. "Taking ideas from the West, and trying to pass them off as genuine, will eventually hit a wall."

Since 2010, Mao has been under an undeclared overseas travel ban, one of the Chinese government's frequently utilized methods of silencing and punishing its critics. He was prevented that year from going to Oslo to attend the ceremony awarding imprisoned Chinese dissident writer Liu Xiaobo the Nobel Peace Prize.

Two years later, he was awarded the Milton Friedman Prize by the libertarian Cato Institute, but was again banned from traveling to Washington, D.C. to accept the award. Unirule's website was also temporarily taken down by authorities at the time.

In recent years, Mao has openly questioned whether the Xi administration has reversed course on decades of Chinese economic reform in favor of companies and entire industries under state control. He has also warned about the revival of a militant neo-Maoist movement reminiscent of the political violence and extreme xenophobia of the 1966-76 Cultural Revolution, when fanatical Mao loyalists targeted ideological opponents and neighbors and relatives turned against each other to survive.

In June last year, the 88-year old economist detailed to The Associated Press the abuse he suffered during the Cultural Revolution, when a gang of young Mao loyalists lashed his father and him with copper-flecked whips.

His public remarks and incessant blogging have attracted protesters to his public events and threats against his safety at home.