An influential Chinese property tycoon who once referred to President Xi Jinping as a "clown" over his handling of the coronavirus outbreak, has been jailed for 18 years on charges of corruption, bribery and embezzlement of public funds.

Ren Zhiqiang, once among the ruling Communist Party's inner circle and the former chairman of Huayuan, a state-owned real estate group, was also fined 4.2 million yuan ($619,003), according to a statement from the Beijing No 2 Intermediate Court on Tuesday.

The court found Ren guilty of embezzling and misappropriating a total of 111 million yuan ($16.3m) and taking and receiving 1.25 million yuan ($184,000) in bribes, according to a notice on the judgement.

It also said Ren had abused his position, resulting in state-owned companies suffering a loss of 117 million yuan ($17.2m) while he made a profit of 19.41 million yuan ($2.9m).

The 69-year-old "voluntarily confessed to all charges", the notice said, and would not appeal the court's decision.

Nicknamed the "Big Cannon" for his outspokenness, Ren disappeared from the public eye in March, shortly after he penned an essay referring to Xi as a clown over a February 23 speech the Chinese leader made about government efforts to battle the coronavirus.

After studying the speech, Ren said he "saw not an emperor standing there exhibiting his 'new clothes,' but a clown stripped naked who insisted on continuing being emperor," according to a version posted by China Digital Times, a US-based website.

The essay did not mention Xi by name.

"This epidemic has revealed the fact that the Party and government officials only care about protecting their own interests, and the monarch only cares about protecting their interests and core position," Ren also wrote.

Beijing's municipal anti-corruption watchdog later said he was under investigation for a "serious disciplinary violation" and had been expelled from the Communist Party in July.

That same month, a Beijing district accused him of using official funds on golf expenses, using office and residential spaces provided for free by businessmen, and unlawfully earning large profits.

Rights campaigners accuse Xi and the Communist Party of using corruption charges to silence dissent.

The space for civil society has become increasingly restrictive since Xi took power in 2012, with hundreds of activists and lawyers detained.