Adoke's lawyer, Mike Ozekhome, said Adoke was arrested by Interpol on Monday, November 11, 2019, after travelling to Dubai for a medical appointment.
The investigation by Nigeria's anti-graft agency relates to the $1.3bn sale of a Nigerian offshore oilfield known as OPL 245 by Malabu Oil and Gas in 2011.
The agency obtained arrest warrants in April for Adoke, former petroleum minister Dan Etete, and an Eni manager.
Eni and Shell jointly acquired the field from Malabu, which was owned by Etete.
The oilfield sale has spawned legal cases across several countries, involving Nigerian government officials and senior executives from ENI and Royal Dutch Shell. Shell and Eni, and their executives have denied any wrongdoing.
Etete has also denied wrongdoing.
In an Italian case, prosecutors accuse former and current executives of Eni and Shell of paying bribes to secure the licence, and allege roughly $1.1bn of the total was siphoned to agents and middlemen.
"We have written to Dubai authorities, the EFCC (anti-graft agency), and the Nigerian authorities to free Adoke to allow him to go on with his medical treatment in Dubai," Ozekhome said.
He added that the arrest warrant had, in fact, expired after being nullified by a court in October, because Adoke was not served with the charges before the warrant was issued.
A government communication office in Dubai did not respond to an email seeking comment. Nigeria's EFCC and Interpol were not immediately available for comment.
Ozekhome said Adoke has appeared in court in Nigeria in the past over the OPL 245 case and was exonerated.