The suspected wrongdoing came to light as part of an internal investigation by Shell but is unrelated to a court case against Shell and Eni in Italy over the acquisition of the oilfield OPL 245, the spokesman said.

"Based on what we know now from an internal investigation, we suspect a crime may have been committed by our former employee ... against Shell in relation to the sale process for Oil Mining Lease (OML) 42 in Nigeria in 2011," the spokesman said in a statement to Reuters.

"We have filed a criminal complaint with the Dutch authorities and are considering other steps we could take."