BEIJING, Sept. 21 (Reuters) - Chinese real estate tycoon and outspoken critic of President Xi Jinping was jailed for 18 years on Tuesday (Sep 22) for "corruption, bribery and embezzlement of public funds", a court statement said.

Ren Zhiqiang - once an elite among the ruling Communist Party's inner circle - disappeared from the public eye in March, shortly after penning an essay that was fiercely critical of Xi's response to the coronavirus outbreak.

Tuesday's verdict said Ren embezzled almost 50 million yuan (US$7.4 million) of public funds and accepted bribes worth 1.25 million yuan, according to a statement from the Beijing No 2 Intermediate People's Court.

It said the 69-year-old "voluntarily and truthfully confessed all his crimes", and would not appeal the court's decision.

He was also fined 4.2 million yuan (US$620,000).

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

Beijing has stepped up its crackdown on civil society since Xi took power in 2012, tightening restrictions on freedom of speech and detaining hundreds of activists and lawyers.

Ren, the former chairman of state-owned property developer Huayuan Group, earned the nickname "Big Cannon" for his outspoken criticism of the Chinese leadership.