Italy’s Supreme Court has thrown out an appeal from Shell and four former Shell managers together with an Eni chief  to stop their trial for alleged corrupt practices in Nigeria.

The long-running graft case revolves around the 2011 purchase by Eni and Shell of Nigeria’s Oil Prospecting Lease (OPL) 245 for an offshore oil field from Malabu Oil and Gas Limited for about $1.3 billion.

Shell and Eni’s appeal was aimed at reversing the trial to the preliminary hearing stage as a result of what it said were procedural errors, but the court decided the appeal was inadmissible.

The former Shell executives involved in the case had claimed a procedural error was made when the original ruling to send the case to court was taken and had applied to Italy’s Supreme Court to void it.

Nine current and former executives or contractors, including Eni’s Chief Executive, Claudio Descalzi, were accused by Italian prosecutors of paying bribes to secure the licence to explore OPL 245, which holds an estimated nine billion barrels of oil but has never entered production.

The trial of the top executives from oil majors Eni and Shell over alleged corruption in Nigeria, which kicked off last month with a brief procedural hearing, was re-adjourned till June 20.