Nigeria sues oil companies, other firms

"The claim dates back to last March and refers to a request to our subsidiary in Nigeria for a payment of about $160 million," ENI said by email.

Nigeria has filed a lawsuit against Italian energy firm ENI, U.S. major Chevron and other international oil firms over some crude exports, ENI, Chevron and a government official said on Tuesday.

"The claim dates back to last March and refers to a request to our subsidiary in Nigeria for a payment of about $160 million," ENI said by email.

"ENI believes the claim has no ground and shall resist in court," it said. "Similar requests have been put forward to several other international oil companies operating in Nigeria."

Chevron said by email: "This matter is the subject of ongoing litigation before the court in Nigeria. We will not comment further on the matter since it is already before the courts."

A Nigerian government official, asking not to be named, confirmed the lawsuit but said he had no details. State oil firm NNPC could not be reached for comment despite repeated attempts to call its spokesman.

Nigerian newspaper Vanguard's website said Nigeria had sued ENI's unit Agip and France's Total for $635 million for allegedly undeclared crude cargoes between 2011 and 2014. It cited court documents.

The lawsuit might further sour the mood of oil majors which have been hit by militant attacks in the Niger Delta oil hub, reducing crude output by a third.