'China faces many institutional dilemmas during its transition from a centrally planned economy to a market one,' Professor Zou said. 'The courts system is especially vulnerable, largely because it has yet to wrest itself from government control, which leaves a great deal of room for misconduct.

'Courts are not independent, and judges cannot have a final say on cases. The situation is quite dire.'

Investigators from the Central Commission for Discipline Inspection - China's top anti-graft watchdog - had detained Pei Hongquan , a vice-president of the Shenzhen Intermediate People's Court, and four other senior judges for allegedly taking or offering bribes for promotion or passing favourable verdicts to those who paid them, the Democracy and Law Times reported.

These four judges, who had also been put under shuanggui - a form of Communist Party disciplinary investigation - were Pei's ex-wife, Li Huiliu , a director of the court, head judge Zhang Tinghua , who was in charge of bankruptcy cases, head judge Cai Xiaoling , who was in charge of cases involving Hong Kong people and foreigners, and Liao Zhaohui .

Judge Zhang was detained an hour after he was promoted to head judge on June 6, the newspaper said. It said the investigation was not stopping there and would delve further into grass-roots courts.

Professor Zou said the exposure of crooked judges could help the anti-corruption campaign.

Supreme People's Court president Xiao Yang said in a report to the National People's Congress Standing Committee that despite some progress in improving judicial accountability through reforms implemented in recent years, misconduct by judges and unfair court rulings were still rampant.