China has indicted Gu Kailai, the wife of deposed Communist Party politician Bo Xilai, for intentional homicide, in the latest development in a political scandal that has shaken the party's once-in-a-decade succession.

Ms Gu and family employee Zhang Xiaojun will be prosecuted for allegedly poisoning British businessman Neil Heywood over a "conflict of economic interests", the official Xinhua news agency said, citing authorities.

"The facts of the two defendants' crime are clear, and the evidence is irrefutable and substantial. Therefore, the two defendants should be charged with intentional homicide," Xinhua said.

It did not give a date for the trial, but a family lawyer said it was likely to take place from August 7 to August 8.

The announcement comes months before the ruling Communist Party unveils its new top leadership.

Mr Heywood was allegedly poisoned after he threatened to expose a plan by Mr Bo's wife to move money abroad, two sources with knowledge of the police investigation said in April.

Ms Gu has been in police custody for months on suspicion of committing or arranging Mr Heywood's murder, although no details of the motive or the crime itself have been publicly released, other than a general comment from Chinese state media that he was killed after a financial dispute.

Mr Bo, the 62-year-old Communist Party chief of Chongqing municipality in south-west China before his dismissal, was widely seen as pushing for a spot in the new leadership until he was felled by the scandal brought to light by his former police chief, Wang Lijun.

Mr Bo was dismissed from his post in March, and suspended from the party's top ranks in April, when Ms Gu was named as a suspect in the November 2011 murder of Mr Heywood, a long-time friend of the couple whose son had studied in the UK with the businessman's help.