The wife of Chinese politician Bo Xilai, whose downfall rocked the ruling elite, has admitted murdering a British businessman and blamed her actions on a mental breakdown, state media said.

Gu Kailai told her trial that she poisoned Neil Heywood after being pushed over the edge by fears that her son was in danger, Xinhua news agency reported late on Friday, more than a day after the trial wrapped up.

The former top lawyer said she would "accept and calmly face any sentence" handed down by the court in the eastern city of Hefei following the seven-hour trial, one of the most high-profile in recent Chinese history.

The verdict will be delivered at a later date, possibly days or weeks away, and while murder carries the death penalty in China, experts say Gu is likely to be spared execution and will instead face a long jail term.

Heywood's murder and allegations of a cover-up sparked the biggest political scandal in China for years and led to the downfall of Bo, who had been tipped to become one of the ruling Communist Party's top leaders.

It exposed deep divisions among China's rulers ahead of a sensitive 10-yearly handover of power later this year, and observers say the party is keen to swiftly draw a line under the controversy.

According to Xinhua, Gu told the court that "during those days last November, I suffered a mental breakdown after learning that my son was in jeopardy".

The son, Bo Guagua, and Heywood got into a dispute over a land project, Xinhua said, citing Gu's testimony.

The court heard that Heywood had demanded 13 million pounds ($20 million), and sent Bo Guagua an email threatening "you will be destroyed", according to a source who was in the room for the hearing and requested anonymity.

According to Gu's testimony, she felt that "I must fight to my death to stop the craziness of Neil Heywood".

Gu then met Heywood for a drink in a hotel room in the southwestern city of Chongqing, where her husband was at the time Communist Party boss, according to Xinhua.

She then killed him by pouring poison into his mouth when he was drunk and scattered pills across the hotel room floor to make it look as if he had overdosed.

The scandal came to light several months after the murder when Chongqing police chief and Bo's right-hand man, Wang Lijun, fled to a US consulate and alleged a cover-up.

"The case has produced great losses to the Party and the country, for which I ought to shoulder the responsibility, and I will never feel at ease," Gu told the court.

A domestic helper, Zhang Xiaojun, also admitted at the hearing to aiding Gu in the murder, said Xinhua. Four police officers also admitted on Friday to covering up Gu's involvement in the killing, a court official said.

After the scandal erupted, Bo was dismissed as boss of Chongqing and from the party's Politburo and placed under investigation. He has not been heard from since April.

Gu's carefully stage-managed trial, and that of four police officers accused of covering up the murder, were being closely watched for any hints on Bo's likely fate, although he has not been implicated in the Heywood murder.

But in several reports on the case released by Xinhua late Friday, totalling around 3,600 words, the former top politician was not mentioned once.

Xinhua said that a panel asked to assess Gu's mental state had concluded that she had been treated for depression and had taken drugs to combat the condition in the past.

However, the experts said Gu still bore "full criminal responsibility".

On Friday four senior police officials in Chongqing admitted covering up the murder to protect Gu.

Tang Yigan, an official with the Hefei Intermediate Court in eastern China, told reporters that a verdict in their case would be given at a later date.

"The defendants admitted that the charge of bending the law for selfish ends was basically correct," he said of the four, named as Guo Weiguo, Li Yang, Wang Pengfei and Wang Zhi.

The court heard how the officers covered up Gu's involvement in Heywood's death by "forging interview scripts and hiding evidence", agreeing to say he died of excessive alcohol consumption.

On Saturday, Chinese Internet censors blocked searches for the worlds "Gu Kailai", "Bo Xilai" and "Neil Heywood" although some web users did manage to comment on the case.

"It is not a judicial trial, it is a political trial and a trial for the privileged," said one web user named A'bang-kunshou.

Gu's trial drew comparisons with that of Chinese leader Mao Zedong's widow Jiang Qing, who along with the three other members of the "Gang of Four" was convicted for fomenting the tumultuous Cultural Revolution.

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