A Chinese court sentenced the former head of one of the country's best known financial newspapers to four years in prison on Thursday, closing a massive media corruption case as Beijing tightens control over the press.

Shen Hao, former president of 21st Century Media, was convicted of extortion and blackmail, "forced transactions" and embezzlement, the Shanghai Pudong New Area People's Court said in a statement on its official social media account.

The verdict comes at a time when China's government is exerting tighter controls over the media -- already one of the most restricted in the world.

Shen is one of the 30 executives at the company, its website and related publications prosecuted by authorities earlier this year.

The firm owns the 21st Century Business Herald, a financial newspaper known for its aggressive investigative reporting.

The staff were accused of demanding payments for positive news from listed firms and prominent companies, while publishing "malicious" attacks on those who refused to cooperate, earlier Chinese media reports said.

"I have no objection to the facts, charges and evidences stated by the prosecutors about the company crime committed by 21st Century Media Co.," Shen told the court Thursday, according to state broadcaster China Central Television (CCTV).

"I'd like to apologise to the firms who fell victim of the company crime," he said.

The practice of businesses paying media to run or delete stories is seen as widespread in China.

But the wave of arrests at 21st Century Media Co. has raised fears of selective enforcement against liberal journalists.

Before going to court, Shen was shown on CCTV "confessing" to being involved in extortion -- treatment that was condemned by journalists and lawyers as violating his right to a fair trial.

Authorities announced a nationwide campaign against media extortion last year.

Le Bing, another former official of the company, got a suspended two-year sentence for embezzlement, the court said.

The trial comes days after a Chinese court handed down a three-year suspended prison sentence to civil rights lawyer Pu Zhiqiang for posts on his social media account that "incited ethnic hatred", sparking increased fears over expression online.

Verdicts on other people related to the case will be announced later Thursday, it added.