Shell has admitted for the first time it dealt with a convicted money-launderer when negotiating access to a vast oil field in Nigeria.
It comes after emails were published showing Shell negotiated with Dan Etete, who was later convicted of money laundering in a separate case.
Shell and an Italian oil company paid $1.3bn (£1bn) to the Nigerian government for access to the field.
Investigators claim $1.1bn was passed to a firm controlled by Mr Etete.
Shell and the Italian firm ENI agreed a deal with the Nigerian government for the rights to exploit OPL 245, a prime oil block off the coast of the Niger Delta.
The government passed on $1.1bn of the money to a company called Malabu, which was controlled by Mr Etete, according to Italian prosecutors.