One of China's most celebrated human rights lawyers was given a three-year suspended prison term on Tuesday in the latest clampdown on critics of the ruling Communist Party.

Police and plainclothes security officials were out in force to try to stop supporters and journalists reaching the court where Pu Zhiqiang was sentenced for "inciting ethnic hatred" and "picking quarrels and provoking trouble".

The verdict is the latest in a widening crackdown on civil society under President Xi Jinping, with more than 200 lawyers and activists detained or called in for questioning since the summer.

Amnesty International called it a "gross injustice".

Pu, who has represented labour camp victims and dissident artist Ai Weiwei, was arrested a year-and-a-half ago over posts on social media between 2011 and 2014.

His secretive trial at Beijing's No. 2 Intermediate People's Court ended Tuesday with a widely-anticipated guilty verdict, but with the sentence suspended for three years.

The ruling means Pu may be sent to jail if he repeats his criticism or runs afoul of police-imposed rules.

"Pu will not have to immediately go to prison, but he is still not a free man," his lawyer Mo Shaoping told AFP.

"We are not satisfied with the verdict because we maintain Pu is innocent."

There were angry scenes around the courthouse, where police set up a cordon to hold back activists and reporters.

- 'There are foreign journalists here' -

"Pu Zhiqiang is a good man! So speaking for the common people is a crime?" yelled one tearful woman as she was roughly shoved into a police van by uniformed officers and plainclothed officials.

"Stop putting on a play, stop acting, there are foreign journalists here," the officer told her.

Another woman stood alone at the centre of a ring of dozens of officers and plainclothes men and shouted "I just won't go! Pu Zhiqiang is innocent!" before being forcibly escorted away.

"China's judicial authorities have been dealing with these cases according to law and the person involved accepted the verdict of the court," Hong Lei, a foreign ministry spokesman, said at a regular briefing.

"Our judicial sovereignty and the decision of the court will not be affected by foreign forces."

For the next three years Pu will be subject to police monitoring and needs permission to leave Beijing.

If he breaks the law or any conditions of his release, he will be sent to prison.

In the comments for which he was tried, Pu said China did not need Communist rule, writing: "Other than secrecy, cheating, passing the buck, delay, the hammer and sickle, what kinds of secrets of governance does this party have?"

He also condemned government policy in the mainly Muslim far-western region of Xinjiang as "absurd".

Ni Yulan, a wheelchair-bound rights lawyer whose 2012 sentencing to nearly three years in prison for "picking quarrels" and "fraud" roused similar international outrage, appeared at the courthouse to show her support.

She sat serenely with her legs wrapped in a blue blanket against the bitter winter cold as her husband Dong Jiqin, also sentenced at the time to two years in prison on similar charges, wheeled her through a pushing crowd of police and plainclothes men who swept her away from reporters.

The state-run Xinhua news agency called it a "light punishment".

It said Pu had "stirred ethnic hatred among Internet users, triggering an antagonistic mentality in many and creating a severe social impact".

But rights groups condemned the sentence.

"Clearly it is positive that Pu Zhiqiang is unlikely to spend another night in jail, yet that cannot hide the gross injustice against him," said William Nee, China researcher at Amnesty International, in a statement.

"He is no criminal and this guilty verdict effectively shackles one of China's bravest champions of human rights from practising law."

Awaiting the verdict in a nearby cafe out of way of police, supporter Xu Chongyang said: "I'm devastated. This case is not just a question of China's internal affairs -- it's a case that implicates all of humanity. Pu Zhiqiang spoke the truth."