LONDON (Reuters) - James Ibori, a former Nigerian state governor jailed in Britain for corruption, has been released after serving the required time in prison.

Ibori, who as governor of oil-producing Delta State from 1999 to 2007 became one of Nigeria’s richest and most powerful men, was serving a 13-year sentence after pleading guilty in 2012 to 10 counts of fraud and money-laundering.

As is normal under British procedures, Ibori had been due to be released from jail this month after serving half his sentence, taking into account pre-trial detention.

Britain’s Home Secretary Amber Rudd had sought to keep Ibori in prison, or electronically tagged, until he returned 18 million pounds ($22 million) of “proceeds of crime”, but that a judge had rejected that proposal, a person familiar with situation said.