By Javier C. Hernández, New York Times–

The Chinese Communist Party said on Tuesday that it was investigating an outspoken property tycoon who accused China’s top leader, Xi Jinping, of having mishandled the coronavirus outbreak.

Party officials said the man, Ren Zhiqiang, was suspected of “serious violations of discipline and law,” a euphemism the authorities often use for corruption and other abuses of power.

Mr. Ren, a longtime party member, disappeared last month after having written an explosive essay describing Mr. Xi as a power-hungry “clown.” The essay, which circulated on Chinese social media sites, said that the party’s strict limits on freedom of speech and its silencing of the news media had exacerbated the epidemic.

A brief statement about the investigation of Mr. Ren, issued by party disciplinary officials in Beijing, did not provide Mr. Ren’s whereabouts, give details about the status of his case or make mention of the essay.

But the decision to investigate him reflects broad unease in the party about growing public criticism of how it handled the coronavirus when it first appeared in December in the central city of Wuhan.

Mr. Xi, who drew scrutiny for the government’s early efforts to conceal the extent of the outbreak, has tried to shift attention away from those missteps and to portray China as a benevolent force leading the global fight against the virus.

The announcement that Mr. Ren, one of the most prominent mainland critics of Mr. Xi, had been placed under investigation prompted immediate concern from many of his supporters.

“It is hoped that the judicial authorities can handle this case strictly and in accordance with the law, and give a convincing demonstration of why the remarks constitute violations of the law and even crimes,” He Weifang, a prominent Chinese law professor, wrote on WeChat, a popular messaging platform.

Mr. Ren is being investigated by the party’s anticorruption watchdog, which Mr. Xi often deploys as a political weapon to ensure the loyalty and commitment of party cadres. It is unlikely that the party will grant Mr. Ren permission to speak with lawyers or relatives while he is under investigation, experts say.

Sophie Richardson, China director at Human Rights Watch, an advocacy group, said Mr. Ren was now “caught in the maw of a party-state ‘disciplinary’ investigation.”

“His case is a powerful example of Chinese authorities’ institutionalized disdain for any semblance of the rule of law,” Ms. Richardson said.

Mr. Ren, 69, the retired chairman of Huayuan Properties, a real estate development company, is a veteran party member and respected entrepreneur. Known in China by the nickname “The Cannon,” he has a long history of angering party leaders, becoming an influential commenter on Chinese social media sites and attracting tens of millions of followers.

In 2016, the party placed him on a year’s probation after he questioned Mr. Xi’s pronouncement that Chinese news media must serve the party. The authorities shuttered his social media accounts.

In his recent essay, Mr. Ren did not refer to Mr. Xi by name. But he made it clear that he was referring to China’s top leader, writing that the party should “wake up from ignorance” and hold its leaders accountable for mistakes during the outbreak.

Mr. Ren denounced the party’s efforts to celebrate its achievements during the crisis, instead of addressing missteps.

“This type of propaganda to cover up a scandal will probably only deceive those who are willing to be deceived,” he wrote. “It can’t work on those who believe in truth and facts.”