Song Pingshun, former chairman of the Tianjin Municipal Committee of the Chinese People's Political Consultative Conference, an advisory body to the parliament in the northern port city of Tianjin, was discovered dead on June 3.

A police investigation determined he had committed suicide.

The CPC Central Commission for Discipline Inspection decided to take the rare step of posthumous expulsion after finding that Song had "abused his public power to seek benefits for his mistress, seriously violating CPC discipline."

"Song, morally degenerate, kept a mistress and helped her obtain money through illegal means," the discipline watchdog said.

Song, 61, a native of northern China's Hebei Province, became the top political adviser in Tianjin, a booming municipality directly under the central government, in March 2006.

He had also served as vice mayor, police chief and secretary of the Tianjin CPC Political Science and Law Commission, which is in charge of the city's police and legal sectors.

The CPC expelled 21,120 members last year for breaking its rules, mainly for taking bribes.

Corruption remains a serious problem in China, the Political Bureau of the CPC Central Committee earlier warned Party members.

More than 1,000 Chinese officials above the county level were punished for corruption during the first five months of this year, up 2.4 percent from the same period last year.

More than 64 percent of the total involved "serious cases" in which officials took more than 50,000 yuan (US$6,600) in bribes or embezzled more than 100,000 yuan in public funds.