BEIJING (AFP) - Bo Xilai, the charismatic but controversial Communist Party leader of China's Chongqing metropolis, has been removed from his post, the state news agency Xinhua said on Thursday.

The move, which comes ahead of a major leadership transition in China's ruling party later this year, follows weeks of intense speculation about Bo's future after a key aide reportedly tried to defect to the United States.

Bo, who is known in China for his populist Maoist revival campaign, will be replaced by vice-premier Zhang Dejiang, according to a brief statement on Xinhua that gave no reason for his dismissal.

The former commerce minister had been seen as one of the leading contenders to join the Communist Party's politburo standing committee -- the apex of political power in China -- later this year.

But that changed on February 6 when Wang Lijun, the former Chongqing police chief who masterminded Bo's crackdown on corruption in the southwestern municipality, visited a US consulate and reportedly asked for asylum.

Wang has been placed under investigation in the wake of the unusually public political scandal.

On Wednesday, as he delivered his closing press conference at the end of the annual parliamentary session, China's Premier Wen Jiabao said officials must "learn lessons" from the incident -- comments seen as a rare public rebuke to a senior party leader.

Bo, the 62-year-old son of a Chinese revolutionary, made a name for himself with his crackdown on corruption, which led to scores of senior officials being jailed in Chongqing -- a sprawling megacity of some 30 million people.

But his revival of "red" culture, which includes sending officials to work in the countryside, red chorales at state-run firms and patriotic television shows, sparked concern among liberals in the party.