The probe team would include forensic specialists and criminal investigators in the fields of detection, trace examination and physical evidence, the agency said.

Deputies from the provincial people's congress and political consultative conference will supervise its progress.

The investigation comes as a stark contrast to Shaoyang officials' original statement that Li's death was suicide. And the order was likely a response to mounting public calls for due diligence in the investigation, particularly from Hong Kong, where thousands have staged protests.

The authorities have not publicly released details of an autopsy on Li's body that was ordered by the Shaoyang city government before the body was cremated on June 9.

Professor Luo Bin of Guangzhou's Sun Yat-sen University, who was involved in the autopsy, declined to comment on the forensic report.

Li was found hanged from a window with his feet on the ground in his hospital room in Shaoyang on June 6.

After 25,000 people took to the streets in Hong Kong on June 10, the Hunan provincial government said on June 14 it would invite 'authoritative organisations' from outside the province to conduct forensic tests and investigations into Li's death.

Andrew Shum Wai-nam, who co-organised the rally, said concerns lingered, despite the government's latest statement. '[Li's sister, Li] Wangling is missing, and many who went to Hunan to fight for [Li's] rights have been detained,' he said. 'I can't see any sincerity in the so-called investigation.'

Shum asked whether any officers linked to Li's detention were being investigated. He described the announcement - made through a Hong Kong-targeted mainland media outlet - as merely a 'superficial act to soothe the Hong Kong public' ahead of a visit by President Hu Jintao to mark the 15th anniversary of the city's handover on July 1.