The OPL 245 oilfield is also at the heart of an ongoing corruption trial in Milan in which former and current Shell and Eni officials are on the bench.

"It is alleged that purchase monies purportedly paid to the Federal Republic of Nigeria were in fact immediately paid through to a company controlled by Dan Etete, formerly the Nigerian minister of petroleum, and used for, amongst other things, bribes and kickbacks," the statement said.

(Reporting by Stephen Jewkes, Ron Bousso, Julia Payne, Paul Carsten, Shadia Nasralla; editing by Jason Neely)