Freed Chinese human rights lawyer Wang Quanzhang has filed a rare complaint seeking charges against two officials, accusing them of torturing him during his secret detention, according to documents seen by AFP.

Detained in 2015 as part of a sweeping crackdown on hundreds of lawyers and rights activists, Wang was released in April after four-and-a-half years behind bars in a case that drew international attention.

This week is also the fifth anniversary of the mass arrest campaign, known as the "709 crackdown". In the years since, China's crackdown on activists and rights lawyers has not subsided.

In the complaint filed to the Supreme People's Procuratorate and the Tianjin People's Procuratorate on Monday, Wang accused two Tianjin Public Security Bureau interrogators, Guo Aiqiang and Fu Rui, of torture to extract a confession, defamation and humiliation.

"On 3 August 2015, the complainant was secretly detained on charges of picking quarrels and stirring trouble, incitement to subvert state power, and subversion of state power," the lawsuit said.

"The complainant was verbally insulted, spat on, slapped, denied toilet access for lengthy periods, prevented from turning over while sleeping, and subjected to various methods to coerce a confession for 15 hours a day for a total of almost a month by Guo Aiqiang and Fu Rui."

Wang was placed in a form of secret extrajudicial detention typically used against dissidents, known as "residential surveillance in a designated location" (RSDL) for six months.

Numerous activists held under RSDL have said they experienced frequent torture, intimidation and coercion, with no accountability from authorities.

That makes the rarity of legal complaints like Wang's even more remarkable, according to activists.

"Wang Quanzhang continues to demonstrate extraordinary courage, undefeatable spirit by filing a complaint against the Tianjin police who committed horrific human rights abuses against him," said Yaqiu Wang, a China researcher at Human Rights Watch.

"Wang probably knows better than anyone that the complaint is unlikely to be accepted by the court and that he is unlikely to get justice from a justice system that is controlled by ... the Chinese Communist Party, and that he could be further punished by filing the complaint."

The Tianjin Public Security Bureau and the Supreme People's Procuratorate did not respond to faxed requests for comment.

A prominent lawyer who has defended political activists and victims of land seizures, Wang was convicted for "subversion of state power" in a closed-door trial that only took place in January 2019. Before then, he had been held incommunicado for more than three years.

Chinese human rights lawyer Wang Quanzhang says he will fight to reunite with his family in Beijing
Chinese human rights lawyer Wang Quanzhang says he will fight to reunite with his family in Beijing AFP / GREG BAKER

In addition to the complaint, Wang has filed a court appeal in Tianjin against his verdict on June 24, according to documents seen by AFP.

In the appeal, Wang asked for his guilty verdict to be overturned, accusing the court of violating legal procedure by refusing to appoint his own defence lawyer -- a right guaranteed by Chinese law.

"I hope that the court can change my verdict, and that prosecutors can open an investigation into the crimes of the police officers," Wang, 44, told AFP.

"The evil wrongdoings of police, prosecutors and judges must be stopped," he said.

"No matter from what perspective, they should not have convicted me or subjected me to such illegal treatment during my interrogation."

Wang, who spoke to AFP on Thursday and Friday, has previously said he was weakened from his lengthy detention and suffered from high blood pressure.

He finally had an emotional reunion with his family in Beijing in late April, after his wife suddenly fell ill.

Authorities had kept him confined in another province for weeks after his release from prison, on the pretext of coronavirus quarantine measures.

The complaint named Jin'an Guesthouse as the location where Wang was secretly detained, and claims that it was a military police training base.

Wang wrote in the document that he was currently confirming the names of more interrogators involved in his torture.

"Some documents had clearly been signed and received (by authorities)," he told AFP.

"But whether the prosecutors decide to open a case is another matter, I can't say for sure."