A joint investigation by UK journalists and a non-profit organisation has unearthed a major scandal involving the sale of the country's largest oil block licence. The OPL 245 oil field -- located on the southern edge of the Niger Delta -- holds an estimated 10 B barrels of crude. Its licence was awarded in 1998 to Malabu Oil and Gas and later sold to Shell and its venture partner Italian giant ENI for $1.3 B. Journalists from the Observer and Finance Uncovered have now discloses that previous government officials benefitted from the sale of the license. The spoils were wired through forex bureaus and two payments of $400 M through JP Morgan in London. Nigeria's anti-graft agency, the EFCC, has filed fresh corruption charges against Shell and ENI for their roles in the scandal. The block is currently owned by the Nigerian government after a temporary court order approved the EFCC's application. Shell and ENI have appealed the order, asking that the field be returned to them.