OSLO (Reuters) - Tesla CEO Elon Musk has clashed with Nicolai Tangen, CEO of Norway's sovereign wealth fund, one of the automaker's top investors, according to a record of the conversation released on Tuesday.

Last June, the fund voted against Musk's $56 billion pay package, the largest for a chief executive in corporate America, at Tesla's annual general meeting, over concerns about its size and structure, among other things.

Later, Tangen invited Musk to participate in a one-day conference in Oslo the fund is organising in April this year, preceded a day before with a home-cooked dinner at Tangen's private residence.

Musk turned the invitation down, writing in an iMessage to Tangen on Oct. 14: "When I ask you for a favor, which I very rarely do, and you decline, then you should not ask me for one until you've done something above nothing to make amends."

"Friends are as friends do."

Tangen replied the day after: "Noted and fully understand. As a large shareholder we cheer for you. Good luck with everything. Best Nicolai."

The exchange was first reported by business website e24.no.

Norges Bank Investment Management (NBIM), the fund's operator, is Tesla's seventh-largest investor, according to LSEG data. The fund had a 0.95% stake worth $6 billion at the end of June, the latest available data from the fund.

Tesla did not immediately respond to a request for comment.

NBIM said it had chosen to publish the exchange "in the light of the increased interest in the case".

"As one sees from the SMSes, some of the dialogue was linked to our voting record at Tesla, where we voted no to Elon Musk's pay package, among other votes," a fund spokesperson said in an emailed statement.