A former railway minister and an ex-deputy governor of eastern China's Shandong Province have been placed on file for criminal investigation and prosecution, the latest in a series of high-level corruption cases.

Liu Zhijun, the ex-railway minister, and Huang Sheng were accused of "serious disciplinary violations," Cui Shaopeng, spokesman for the Central Commission for Discipline Inspection of the Communist Party of China, said yesterday.

Both have undergone "double designation" - a special investigative procedure for Party officials under which they are required to confess or explain wrongdoings at a certain time and place.

Liu, 59, an advocate of high-speed train travel, was sacked in February 2011 as the railway minister and then detained amid a graft probe that involved a series of railway projects.

Late last month, the State Council said Liu should also be responsible for the bullet train crash last July that killed 40 people in the eastern city of Wenzhou. But the Party's top disciplinary watchdog did not disclose more details about his case.

According to his official biography, Liu joined the Party at age 20 and was appointed the railway minister in March 2003.

The investigation of Liu came a month after a corruption probe into businesswoman Ding Shumiao, 55, a member of Shanxi Province's political advisory body. Since 2000, she reportedly expanded into railway construction and established Broad Union Group, which became China's only producer and maintainer of train wheel sets in 2006 and won contracts worth 2 billion yuan.

Liu is said to have received more than 800 million yuan (US$126.7 million) in bribes to offer her priority in contracts and engage in internal trading.

Liu Zhixiang, Liu Zhijun's younger brother, former head of the railways bureau in the central city of Wuhan, was also implicated in the probe. He was sentenced to death in 2006 with a two-year reprieve after convictions of conspiracy to assault, embezzlement and bribery.

The Party discipline agency didn't give details about the graft case again Huang either, but online rumors said he took bribes of US$9 billion, kept 46 mistresses and owned 46 properties.

Huang, 58, suddenly disappeared from public view late last year before central authorities announced on December 1 that he had been held for serious discipline violations.

Huang, a native of Weihai in Shandong, joined the Communist Party in 1975 and started his political career as a military cartographer.

He was promoted to government official in 1984, assigned as the mayor of Shandong's Dezhou in 1996 and elected as the province's deputy governor in 2007.

According to Cui, 2011 saw a total of 4,843 Chinese officials above the county head level punished for discipline violations. Cases involving 777 of these officials have been transferred to judicial departments.

About 1,480 cases of illegal land appropriation and demolition were handled in 2011, and 509 people involved were held accountable.

Food and drug safety is another concern for discipline authorities.

3,895 people were held accountable for nearly 6,000 food safety violations last year, while 3,680 people were held accountable for more than 9,000 cases of drug safety violations.

While hailing the progress of the country's anti-corruption efforts, Cui Shaopeng admitted corruption is still frequently seen in some government departments and sectors as economic activity booms in the fast-developing country.

"The public has pinned its hopes on the fight against corruption, but corruption cannot be rooted out in the short-term. The fight against corruption remains severe and the tasks involved are heavy," said Cui.

(Shanghai Daily contributed to the story)