Former governor James Onanefe Ibori of Delta State will become a free man in December this year.
James Ibori was jailed for money laundering offences by Southwark Crown Court in London, UK in 2012.
Some of his assets were confiscated following allegations of money laundering.
A British court was told on Friday that Ibori would appeal against his conviction on the grounds that British police and lawyers involved in his case were themselves corrupt.
Ibori became one of Nigeria’s richest and most powerful men after his stint as Delta State Governor.
He is currently serving a 13-year sentence after pleading guilty in 2012 to 10 counts of fraud and money-laundering.
While in office, Ibori allegedly acquired plush properties in Britain, the United States, South Africa and Nigeria.
He is the most senior Nigerian politician to have been held to account for the corruption that has ruined Nigeria.
Stephen Kamlish, a lawyer for Ibori associate and convicted money launderer Bhadresh Gohil, said some documents showed there had been widespread police corruption followed by a cover-up that was still going on now.
The main allegation is that a police officer involved in the Ibori probe took payments for information in 2007 from a firm of private detectives working on Ibori’s behalf.
At the time, Ibori had not been arrested and was still in Nigeria, but knew that British police were investigating his finances.
Kamlish claimed prosecution lawyers had known there was evidence of police corruption but failed to disclose it to defense lawyers.
Under British procedures, Ibori is due to be released in December after serving half his sentence, taking into account pre-trial detention.
After his release, Ibori may still not return to Nigeria as yet.