Nigeria’s financial crime watchdog has filed new corruption charges against Royal Dutch Shell, Eni and others regarding the $1.3 billion purchase of a long-disputed oil field in 2011, according to court documents released March 2.

The charges of conspiracy to commit a felony and official corruption were made after an investigation by Nigeria’s Economic and Financial Crimes Commission (EFCC) found new evidence, Jonson Ojogbane, an EFCC senior prosecutor named in the documents, told Reuters by telephone.

Eni said it had not received any notification about the charges and that the company “reaffirms the correctness of its conduct” in the acquisition of the license.

Shell did not immediately respond to requests for comment.

The case is the latest of several inquiries, following those by Dutch and Italian authorities, into the 2011 purchase of Nigerian oil prospecting license OPL 245 Block, which could hold up to 9.23 billion barrels of oil, according to industry figures.

A Nigerian court ordered in January the seizure of the oilfield assets and transfer of operations to the federal government on the request of the EFCC.

On March 13 a court will rule on a request by Shell and Italy’s Eni to lift the temporary seizure.

The targets of EFCC’s new charges include Shell’s local subsidiary, Eni and its local subsidiary, directors of those companies, a Nigerian former oil minister and a former justice minister.

The court filing alleges those involved conspired to commit a felony and violated corruption laws by paying $801 million to Nigerian officials for OPL 245 in 2011.

The oilfield’s license was initially awarded in 1998 by former Nigerian oil minister Dan Etete to Malabu Oil and Gas, a company in which he held shares and which is also named in the new charges.

Reuters could not immediately reach Etete or Malabu for comment.

The license was then sold for $1.3 billion in 2011 to Eni and Shell. A British court document has shown that Malabu received $1.09 billion from the sale, while the rest went to the Nigerian government.

Last month Eni backed CEO Claudio Descalzi after judicial sources said that prosecutors had asked for him to be tried over alleged corruption in the OPL 245 case. Descalzi has denied any wrongdoing.