Sun Yingxia, 64, could have had little idea of the 12-day ordeal that awaited her when she went to the Tianganghu township government in Sihong county, Jiangsu Province, for "negotiations" on the demolition of her house on June 1 last year.

Controversy over 'black jails' continues

Sun and two other villagers, who had also refused to sign the demolition agreement, insisted on being compensated with the equivalent units of land, forcing the negotiations into a deadlock.

Later Sun and the two villagers were forced by a dozen or so people into a van, according to a Southern Metropolis Daily report on April 27. They were driven for more than an hour to an enclosed yard some 50 kilometers from the township government building.

Sun was quoted by the report as saying she was shut in a small, windowless room for 12 days and suffered mental and physical torture.

"Several of the village and township leaders were at the scene when we were dragged into the car," Sun told the newspaper. "They watched us being taken away."

A member of the Sihong Public Security Bureau told the Global Times that they had no information about the secret yard in Sihong.

Sources told the Southern Metropolis Daily the yard had previously been used as a "petitioner study center" – a secret jail for petitioners. But in recent years, it has not only been used to imprison petitioners, but also members of nail households, a term given to people who refuse to make way for demolitions, the report said.

A member of staff at the Sihong Bureau of Letters and Calls – the petition office – told the Global Times they had not heard of the yard before the report. "Now a lot of people are talking about it in Sihong," he said, "but we have no information about this place."

He asked the Global Times to call the local government, which could not be reached as of press time.