One of China's highest-profile trials in decades opens on Thursday when the wife of the disgraced Chinese politician Bo Xilai appears in court charged with murdering a British businessman.

Gu Kailai, a former international lawyer whose life of wealth and privilege ended abruptly when she was accused earlier this year of poisoning Neil Heywood, will stand in the dock knowing that she is all but certain to be found guilty.

Analysts say the trial, which is expected to last just a day or two, is an attempt to draw a line under a scandal that has sent shockwaves through the Communist party and exposed deep rifts ahead of a power handover.

It has evoked comparisons with that of Chinese leader Mao Zedong's widow Jiang Qing, who along with three other "Gang of Four" leaders was convicted for fomenting the tumultuous Cultural Revolution.

She received the death penalty but this was later commuted to life in prison, as is often the case for high-profile defendants in China.

In a rare concession, British diplomats will be allowed to attend Thursday's hearing in Hefei, capital of the eastern province of Anhui. It will open in the morning with 100 guests and some media, said a court spokeswoman.

The scandal brought down Gu's husband Bo, a high-flying but divisive Communist official known for his aggressive crackdown on organised crime and for a Maoist-style "red revival" campaign that alienated party moderates.

He is now under investigation for corruption, but with Gu going to trial, some analysts believe she will bear the harsher consequences while Bo will be dealt with more lightly or after the leadership transition this autumn.

"The fact that they are putting her to trial means the top leadership has reached some kind of basic agreement," said Steve Tsang, a professor and director of the China Policy Institute at the University of Nottingham.

"They are really focusing on getting Gu Kailai to pay. My bet is that Bo will get off relatively lightly and they are going to park Bo Xilai's case until after the succession, the party Congress."

The Hong Kong-based South China Morning Post daily said this week that Gu had confessed to the murder and to "economic crimes", although she is charged only with intentional homicide.

State news agency Xinhua has said there is "irrefutable and substantial" evidence that she along with family aide and codefendant Zhang Xiaojun poisoned Heywood.

It said she had "economic conflicts" with the Briton and feared for the safety of her son Bo Guagua, 24, who is believed to be in the United States where he recently completed a master's degree.

The younger Bo told CNN this week he had submitted a witness statement to his mother's defence team, and that he believes the "facts will speak for themselves" in the case.

Though Gu faces the death penalty, legal experts say she will likely receive a commuted death sentence that translates into 10 to 15 years in prison, with her concern for her son's safety providing a mitigating circumstance.

Given her elite stature -- her father was a renowned Communist general -- she may also enjoy comfortable imprisonment conditions.