China on Tuesday sentenced a high-profile activist — who was investigating the deaths of school-children in the 2008 Sichuan earthquake — for five years in prison.

Tan Zuoren was sentenced on the charges of inciting subversion of state power, in connection with essays he wrote in the aftermath of the 1989 Tiananmen Square protests. But his attorney said Mr. Tan was detained for compiling a list of school-children who died in the massive earthquake that struck Sichuan province in May, 2008, killing at least 90,000 people.

More than 7,000 schools — many newly built — collapsed in the quake, killing at least 5,300 school children, according to official figures. Many parents say the death-toll is far higher, and have blamed poor construction for the collapse of the schools. Local journalists reported that schools in Sichuan suffered far greater damage than other public buildings: hundreds of newly-built schools collapsed, even as many surrounding buildings withstood its impact.

Mr. Tan was among a number of activists who were calling on the government for a full investigation into the deaths of the children.

But many activists and parents of victims who have been leading the campaign have been detained or imprisoned. In July 2008, Huang Qi, another activist, was arrested on the charge of illegally possessing state secrets.

“Tan thinks one of the reasons behind this case is that he was leading an investigation into the poorly built schools after the earthquake, which would have embarrassed the local government in Chengdu,” his attorney Pu Zhiqiang told the Associated Press.

Mr. Tan’s wife, Wang Qinghua, said her husband had “only exercised his freedom of expression and addressed corruption from his own conscience.”

Human rights groups have criticised the trial process. Many witnesses who Mr. Tan had called were prevented from testifying in the August 12 hearing in Chengdu, Sichuan’s capital.

“The Chinese authorities cannot continue to claim that they are dealing with human rights defenders according to the law when they violate so many of their own legal procedures in cases like this,” said Roseann Rife, Asia-Pacific Deputy Director at Amnesty International.

One of the witnesses prevented from testifying was the artist Ai Weiwei, who has been assisting Mr. Tan in the post-earthquake investigation. Mr. Ai said he was detained in his hotel room the night before the trial, and assaulted by police officers. He subsequently had to undergo surgery in Munich for a cerebral haemorrhage following the attack on him.

“Tan Zuoren, today every one of 5,000 orphans is your child; they are all calling out for you,” he said on Wednesday, in a message posted on the website Twitter.

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