LAGOS, Nigeria — Nigeria is suing several major oil companies for $12.7 billion of oil that allegedly was exported illegally to the United States between 2011 and 2014, officials said Tuesday.

The Federal High Court in Lagos begins hearings next week in cases filed against Nigerian subsidiaries of US multinational Chevron, British-Dutch Shell, Italian ENI’s Agip, France’s Total, and Brasoil of Brazilian Petrobas, according to the court register.

Oil companies did not immediately respond to requests for comment.

Officials familiar with the cases said Nigeria’s government alleges that the companies did not declare more than 57 million barrels of crude oil shipments. That was deduced from audits of declared exports and what was unloaded in the United States.

Some shiploads registered less when they left Nigeria and more on reaching the United States, while some entire shiploads were undeclared in Nigeria, said the officials, who spoke on condition of anonymity because the cases still are in court.

Michael Kanko confirmed that his US-based ImportGenius database was used by attorneys to confirm declarations made to US customs by shippers and importers.

Law professor Fabian Ajogwu is representing the Nigerian government in the case against Chevron, which comes up first on Sept. 30.

Associated Press