WASHINGTON — Shortly before Donald Trump secured the Republican nomination last summer, his campaign chairman offered to provide private briefings on the race to a Russian billionaire with Kremlin ties, his spokesman confirmed to NBC News.

The offer appeared in emails between then campaign chairman Paul Manafort and one of his employees, some of which suggested Manafort was seeking to use his role to make money, the Washington Post reported. The spokesman, Jason Maloni, said the emails, which had been turned over to congressional committees, showed nothing improper.

The Post said the billionaire was Oleg Deripaska, an oligarch in Putin's inner circle. NBC News has reported that Manafort had business dealings with Deripaska, who was once denied entry to the United States because of alleged mafia links.

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Maloni said he did not dispute that the billionaire was Deripaska.

"If he needs private briefings we can accommodate," Manafort wrote in the July 7, 2016, email, the Post reported.

Other exchanges discussed money Manafort believed he was owed by Eastern European clients, the Post said.

Just after Trump named Manafort as a campaign strategist, the Post reported, Manafort referred to his positive press and growing reputation and asked his employee in an email, "How do we use to get whole?"

Maloni told NBC News: "It is no secret Mr. Manafort was owed money by past clients after his work ended in 2014. This exchange is innocuous."

"How do we use to get whole?"

Maloni said other campaign emails show that Manafort turned down a proposal from another campaign aide for Trump to meet with Putin and other top Russian officials.

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Manafort's business ties to Deripaska were detailed in a 2014 legal action in the Cayman Islands.

In the Cayman Island court petition, a company controlled by Deripaska alleged it invested $18.9 million in 2008 in a firm in which Manafort had an interest, Pericles Emerging Markets, to acquire a company called Black Sea Cable. The petition also alleged companies controlled by Deripaska paid $7.35 million toward management fees for Manafort and his partners. The court filing was seeking an accounting of the money.

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Manafort was questioned by Cayman Islands officials in the matter earlier this year, his lawyer has said publicly.

Manafort told NBC News in August of 2016 that the matter was closed.

Deripaska had been repeatedly denied a visa to enter the United States over his alleged ties to organized crime, current and former officials tell NBC News.

Several officials told NBC News he has since been given diplomatic status by the Russian government, allowing him to enter the U.S. with immunity.