Rights groups said Mr Chen. who is blind, did not get a fair trial

Chen Guangcheng was sentenced to four years and three months for "damaging property and organising a mob to disturb traffic", state media said.

Mr Chen had accused officials in Shandong province of breaking family planning laws in their enforcement of the one-child policy.

His trial last week took two hours, and his lawyers were arrested before it.

One of the lawyers who was arrested, Li Fangping, told the BBC that Mr Chen had been represented, against his will, by two state-appointed lawyers in the closed-door proceedings.

Rights group Amnesty International said that Mr Chen had not received a fair trial.

Mr Chen's wife, who was not allowed to attend the trial, said she was shocked by the verdict.

"I thought they were going to sentence him even though he's innocent, but I never expected such a heavy sentence," she told Reuters news agency.

Mr Li said he was outraged by the sentence. "The whole justice system has acted totally illegally in Chen Guangcheng's case," he told the Associated Press news agency.

Sterilisation

The charges against Mr Chen related to protests that occurred after he was detained in September 2005.

He had accused local health workers in Linyi city in Shandong of forcing people to have late-term abortions or sterilisations in order to enforce the one-child policy.

His allegations were covered in the international media, including an article in Time Magazine which claimed some 7,000 people had been sterilised against their will in the province.

In 2006, the magazine named Mr Chen as one of the world's 100 most influential people for exposing the problem.

Several workers were later arrested or sacked over the claims, state media reported, acknowledging "successive complaints" about illegal practices in Linyi.

China brought in its one-child policy 25 years ago, in a drive to curb population growth. But forced sterilisation and abortion are illegal.