The corruption trial of China's onetime political superstar Bo Xilai combines elements of unusual openness with traditional controls rooted deep in the one-party state and the country's long history, analysts say.

Bo, who held sway over nearly 30 million people as the top Communist in the megacity of Chongqing before his spectacular fall, faces charges of bribery, embezzlement and abuse of power in a scandal that has rocked the ruling party.

It is not the first time the all-powerful Communist Party has had to air its dirty laundry in public, but the level of openness in the deliberations has caught many by surprise.

"Of course this is not real justice that is being played out," said Nicholas Bequelin, Hong Kong-based senior researcher at Human Rights Watch. "This is political theatre."

Unlike previous high-profile trials, the court is providing regular but delayed transcripts on a verified social media account, offering observers a window on proceedings often seen through the distorted lens of limited state media coverage.

They have also given Bo himself an outlet for the details of his defence to reach a wide audience.

"No one expected that Bo Xilai would be given that amount of freedom to defend himself," Bequelin told AFP.

"Nonetheless the legal parts have been surprisingly good because there is a real legal process taking place there, at least in the courtroom, even though the outcome has already been decided and predetermined."

The approach has both advantages and risks for China's rulers, he added.

"Having a good trial like this, something that really looks like a real trial, will help confer legitimacy to the outcome and that's in the interest of the Party," he said.

"The cost is that it raises the expectations of the public in terms of administration of justice. Because it gives people ideas, first of all about the virtues of defence rights."

Margaret Lewis, a professor at Seton Hall Law School in the United States, contrasted Bo's trial with those of two other once high-flying officials -- Chen Liangyu, a former party secretary for Shanghai and Chen Xitong, mayor of Beijing at the time of the Tiananmen massacre -- who were convicted of corruption-related charges.

"Both of those trials were carried out completely behind closed doors," Lewis said in an e-mail. "Bo, in contrast, is at least being given an opportunity to publicly proclaim his innocence."

Chinese courts normally rely on written statements rather than live witness appearances, and Bo's cross-examination of key prosecution witness Xu Ming was unusual, she added.

But the message from the courtroom was still being controlled by the government, she stressed. "If, for example, Bo took this opportunity to name officials who have engaged in corrupt dealings, I would be absolutely shocked if that information made it into the transcript released for public view."

Chinese voices have seized on the hearings as a sign the country's legal system is changing.

The completeness of the transcripts released via social media "is record-breaking for a Chinese criminal court", well-known lawyer Chen Youxi said in comments posted online. "It will have a far-reaching impact on Chinese trials of public officials."

But Nicholas Howson, who teaches law at the University of Michigan, said the trial remains a "public performance" that was "very much in line with governance practice in China stretching back into imperial times".

"A sudden and secretive un-personing of a political figure or a Stalinesque show trial" were no longer possible in modern China, he said via e-mail, but it was still "far less than the kind of proceeding that the Anglo-American system at least aspires to have".

China has in the past allowed high-profile defendants a dramatic voice at key moments, analysts said.

Jiang Qing, widow of the revered Mao Zedong, founder of Communist China, put in a melodramatic performance at her trial with other members of the infamous Gang of Four, parts of which were shown on television.

Bo's spirited performance might be a intended as a "gamble" that the party would allow a lighter sentence so that the public felt his defence was meaningful, Lewis said.

"At a minimum, it appears that he has sought to use this trial as a vehicle for having a voice after being completely out of public view for over a year. Whatever the outcome of the trial, he has achieved that goal."

Xu Ming: prawn seller turned key witness against China's Bo
Beijing (AFP) Aug 23, 2013 - Bo Xilai's chief accuser at his corruption trial in China is a former prawn seller said to have made more than a billion dollars since linking up with the politician in the 1990s.

Born in April 1971 in the industrial port city of Dalian, Xu Ming spent his childhood in the countryside, the Hong Kong-based Mirror Books website said.

According to the website of Shide Group, the conglomerate Xu founded, he studied international trade at university.

His first job was a salesman in charge of Japanese clients at a prawn exporting firm in Dalian, according to Mirror Books, and he later established his own seafood trading company, although it was not a great success.

Shide Group was set up in 1992, around the same time that according to the Wall Street Journal Xu was introduced to Bo Xilai, then Dalian's mayor, and his wife Gu Kailai by a Taiwanese-American businessman, and they developed a close relationship.

The firm grew into a national conglomerate in the following eight years thanks to local government policies and contracts linked to Bo's plan to revamp Dalian into a shipping, fashion and information technology hub to impress the Party's top leadership, the paper said.

Shide now operates in sectors including construction material, petrochemical, finance, sports and home appliances.

In an example of how close Xu was to the Bo family, he accompanied Gu and her son Bo Guagua on a trip to Britain more than 14 years ago to scout out schools for the boy, according to the Wall Street Journal.

Bo is accused of accepting 20.7 million yuan ($3.4 million) in bribes from Xu, who testified for the prosecution on Thursday.

According to transcripts of evidence provided by the court trying Bo in Jinan, Xu gave the family millions over the years, including paying off a credit card bill of more than $50,000 run up by Guagua, and buying the boy an 80,000 yuan ($13,000) Segway scooter.

He said that when Gu expressed a desire to buy a villa in France, he provided $3.2 million for her to do so.

On its website Shide Group said that Xu was listed as the 85th richest person in China in 2010, worth $1.6 billion.

He faces charges of illegal business actions, the court in eastern China heard.