Nigerian legislators have begun an investigation into the alleged importation of contaminated fuel into the country, part of efforts to resolve issues causing a rift between an oil refinery owned by Africa’s richest man Aliko Dangote and the industry regulator. A legislative committee tasked with carrying out the probe is also looking into allegations of the “indiscriminate issuance of licenses and the alleged unavailability of international standard laboratories” blamed for such contaminated products, its chairman said in the capital of Abuja. The committee called on parties in Nigeria’s petroleum sector to “deescalate tensions” that have been deepened in recent weeks.