A Russian metals billionaire sued President Donald Trump’s former campaign chairman on Wednesday, alleging he and a partner misappropriated at least $18.9 million of funds the Russian had invested.

Oleg Deripaska alleged in a lawsuit filed in the New York state court Wednesday that Paul Manafort, the former campaign manager, and his long-time partner Richard Gates “vanished” the money invested by the Russian businessman in the late 2000s. The suit, filed by Mr. Deripaska’s Cyprus-based Surf Horizon Ltd., seeks $25 million in punitive damages and other compensatory damages.

“It was only in the past year that Surf obtained access to evidence showing that, not only had Messrs. Manafort and Gates failed properly to supervise the investment, but each had secretly and improperly profited from it,” said a spokesman for Mr. Deripaska’s investment group.

Mr. Gates didn't respond to a request for comment.

Jason Maloni, Mr. Manafort’s spokesman, said the filing was a surprise. “This is a commercial matter which we thought had been addressed and resolved years ago,” he said. “We will respond, if we must do so, in the appropriate manner.”