* State prosecutors open criminal investigation
* Expulsion from parliament removes Bo's immunity from prosecution
* Announcements made two weeks before Communist Party congress
* Bo's wife, police chief, jailed over businessman's murder
BEIJING, Oct 26 (Reuters) - China moved quickly on Friday to announce it had formally begun a criminal probe into disgraced former senior politician Bo Xilai, hours after expelling him from the largely rubber stamp parliament and so removing his immunity from prosecution.
The announcements pave the way for Bo, once a contender for top leadership in the world's second largest economy, to face trial and likely a long jail sentence on accusations of corruption and abuse of power.
A brief report by the state-run Xinhua news agency said state prosecutors had ``decided to put Bo Xilai under investigation for alleged criminal offences''.
It added that they had ``imposed coercive measures on him in accordance with the law'', likely a reference that he was now officially in detention.
Bo's wife, Gu Kailai, and his former police chief, Wang Lijun, have both been jailed over a scandal that stems from the murder of British businessman Neil Heywood while Bo was Communist Party chief of the southwestern city of Chongqing.
The government last month accused Bo of corruption and of bending the law to hush up the murder.
The latest move comes a fortnight before the Communist Party holds a congress, which opens on Nov. 8, that will unveil the country's new central leadership.
Bo, 63, was widely seen as pursuing a powerful spot in the new leadership before his career unravelled after Wang fled to a U.S. consulate for more than 24 hours in February and alleged that Bo's wife had poisoned Heywood.
Bo, a former commerce minister, used his post in Chongqing since 2007 to cast the sprawling, haze-covered municipality into a showcase for his mix of populist policies and bold spending plans that won support from leftists yearning for a charismatic leader.
Xinhua provided no other details, such as what charges Bo may face, saying only that the investigation was under way.
Earlier in the day, Xinhua said the Standing Committee of the National People's Congress, China's parliament, ``announced the termination of Bo Xilai's post'' as the deputy to the parliament.
As a member of that body he had enjoyed immunity from prosecution.
Before Bo is charged and tried, investigators must first complete an inquiry and indict him, but China's prosecutors and courts come under party control and are unlikely to challenge the accusations.
A lawyer for Bo, who has been employed by the family to represent him, said on Thursday he was unable to say whether the government would allow him to represent Bo when the case comes to trial.
``It's theatre,'' said Nicholas Bequelin, a researcher at Human Rights Watch, a New York-based advocacy group, who spoke before Bo's expulsion and criminal probe were announced.
``The judiciary grinds into action only when the outcome has been determined. There is no indication we will see a genuine trial because Bo knows too much.''
An official account of Wang's trial in September said Wang fled to the U.S. consulate in Chengdu, southwest China, after Bo beat him and stripped him of his police job following Wang's decision to confront Bo with the murder allegations against Gu.
Wang had spearheaded Bo's controversial campaign against organised crime, a prominent plank in Bo's barely concealed campaign to join the topmost ranks of the Communist Party.
Bo was dismissed from his Chongqing post in March, and suspended from the party's top ranks in April, when his wife was named as an official suspect in the murder in November of Heywood, a long-time friend of the couple who also helped their son Bo Guagua settle into study in Britain.
Bo has disappeared from public view since he was dismissed and has not had a chance to respond publicly to the accusations against him.
The removal of Bo has disrupted the Communist Party's usually secretive and carefully choreographed process of settling on a new central leadership.
Sharply dressed and courting publicity, Bo stood out in a party of stolid conformists, and he promoted Chongqing as a bold egalitarian alternative to China's current pattern of growth.
But Bo's promotion of ``red'' culture inspired by Mao Zedong's era and his campaign-style crackdown on crime prompted fears that he was rekindling some of the arbitrary lawlessness of the Cultural Revolution in the 1960s - a criticism that Premier Wen Jiabao spelled out before the public in mid-March.