Fallen Chinese politician Bo Xilai has written a defiant letter from prison vowing to clear his name just days ahead of a court verdict following a high-profile corruption trial, Hong Kong media reported on Thursday.

Formerly a top-ranked member of the ruling Communist Party, Bo -- almost certain to be found guilty on Sunday -- said in the letter to family members that his name will "one day" be cleared, the South China Morning Post reported.

Bo, once tipped for membership of China's most powerful political body before his dramatic fall from grace last year, indicated that he expects to receive a jail term, writing that he will "wait quietly in the prison".

"My father was jailed many times. I will follow his footsteps," the SCMP cited Bo as writing.

Bo's father, Bo Yibo, was a celebrated revolutionary leader who was jailed several times during China's tumultuous Cultural Revolution, which was launched in the 1960s.

"Father and mother have passed away, but their teachings continue to serve me well. I would not disgrace their glorious past," Bo said in the letter, according to the SCMP.

Bo also thanked his family for their support during his dramatic five-day trial last month, where he mounted a fierce defence against charges of bribery, embezzlement and abuse of power.

AFP was not able to verify the contents of the letter, which the newspaper said was written last week.

Though a guilty verdict is almost certain, his punishment remains in question. The charges against him mean he could be handed a death sentence, but several analysts said they expect him to receive a prison term of around 20 years.

The downfall of Bo, 64, who was the top official in the southwestern megacity of Chongqing and one of China's most prominent politicians, exposed the ruling party to allegations of graft at a senior level.

The scandal added to divisions ahead of a once-in-a-decade leadership transition that saw Xi Jinping installed as party chief in November.

Bo fell from grace after his police chief fled to a US consulate. His wife was later convicted of the murder of a British businessman.

In his trial, Bo vehemently denied the charges against him while the prosecution accused him of corruptly obtaining 26.8 million yuan ($4.4 million) and covering up the killing committed by his wife.

Revelations of private jet flights, luxury villas and gifts of rare animal meats held Chinese Internet users spellbound, with the court's weibo account gaining more than half a million followers.

Bo's defiance over the course of the hearings astonished a public unfamiliar with the open airing of top-level intrigue and was in stark contrast to previous Chinese political trials, in which most defendants have humbly confessed their crimes in opaque court proceedings.

He dismissed testimony by his wife Gu Kailai as "insane", launched a scathing attack on his former police chief Wang Lijun as "full of lies and fraud", and compared another prosecution witness to a "mad dog".

At the close of the trial prosecutors said Bo's crimes of bribery, embezzlement and abuse of power were "extremely serious" and there were no mitigating factors.

Though a guilty verdict is almost certain, his punishment remains in question. The charges against him mean he could be handed a death sentence, but several analysts said they expect him to receive a prison term of around 20 years.

Prior to his ouster, Bo was one of 25 members of the party's Politburo, China's second-highest body. The last former Politburo member to be tried for corruption, Chen Liangyu, received an 18-year prison term in 2008.