Etete, who was convicted of money laundering in France in 2007, could not be contacted for comment and his lawyers did not immediately respond to requests for comment.
According to Reuters, one of the oil industry's biggest corruption trials revolves around a Nigerian offshore licence known as OPL 245, which Royal Dutch Shell and Italy's Eni bought in 2011.
Italian prosecutors accuse former and current executives of the two energy giants of paying bribes to secure the licence.
Shell and Eni, and their executives have denied the accusations and any wrongdoing.
Below are a list of legal actions that have arisen from the award of OPL 245:
* Some key issues related to the OPL 245 case came to light in two separate civil suits filed shortly after the 2011 deal by a Nigerian, Emeka Obi, and a former Russian diplomat, Ednan Agaev, who said they were owed millions of dollars by a Nigerian company, Malabu Oil and Gas, for arranging meetings with Shell and Eni in relation to the licence, court filings show. Obi was awarded at least $100 million for his work as a "dealmaker", the court records show. Agaev reached an out-of-court settlement.
* Nigeria filed a case in London against U.S. bank JPMorgan for its role in transferring more than $800 million of government funds to Malabu. JPMorgan acknowledged it knew former minister Dan Etete would benefit when it transferred the funds to the company, according to a court document seen in April 2018. JPMorgan did not provide a comment on the filing. Etete, who was convicted of money laundering in France in 2007, could not be contacted for comment and his lawyers did not immediately respond to requests for comment.
* In May 2018, Nigerian civil rights group Human & Environmental Development Agenda (HEDA) launched a legal case aimed at forcing the government to revoke the award of OPL 245.
* In May 2018, the main trial in Milan started, in which Eni Chief Executive Claudio Descalzi, former Shell exploration chief Malcolm Brinded and 11 other defendants, as well as the two companies, were accused by Italian prosecutors of paying bribes to secure the licence. All the accused denied wrongdoing.
* In September 2018, in a separate trial in Milan, Emeka Obi and Italian Gianluca Di Nardo were sentenced to jail in a corruption case related to OPL 245. Obi and Di Nardo appealed the ruling.
* In December 2018, Nigeria filed a $1.1 billion lawsuit in a London commercial court against Shell and Eni in relation to the oilfield deal. Shell said the transaction was fully legal and Eni said it rejected any allegation of impropriety or irregularity.
* In March 2019, Dutch prosecutors said they were preparing criminal charges against Shell over OPL 245.
* In April 2019, a Nigerian judge issued arrest warrants for Dan Etete, another former minister and an Eni manager over the sale of OPL 245. Eni called the move disproportionate and detrimental to the rights of its manager. Etete could not be contacted for comment and his lawyers did not immediately respond to requests for comment.
* In July 2019, Eni Chief Executive Descalzi sued a former legal adviser to the Italian company for defamation after excerpts of the lawyer's written testimony relating to the Nigerian case were published in several newspapers.