One of Russia's most powerful tycoons -- barred entry to the U.S. for years due to U.S. government concerns about possible ties to organized crime -- visited the country twice this year under secret arrangements made by the Federal Bureau of Investigation.

Aluminum magnate Oleg Deripaska met with FBI agents in August and earlier this month as part of a continuing criminal probe, according to two administration officials. The focus of that probe couldn't be learned.

Mr. Deripaska used the opportunity of his recent U.S. visits to meet with top executives of U.S. investment banks Morgan Stanley and Goldman Sachs Group Inc. The aluminum giant he controls, UC Rusal , is preparing for an initial public offering, a vital part of Mr. Deripaska's efforts to save his debt-burdened business.

The U.S. trips came at an opportune moment to help reassure bankers his visa difficulties may be easing. Mr. Deripaska's visa troubles are a potentially sensitive issue for investors, bankers say.

Mr. Deripaska also stopped in Detroit to meet with top executives at General Motors Co. to discuss the sale of a stake in its Adam Opel AG unit to a Russian-backed consortium that includes Mr. Deripaska's AO GAZ auto maker, people familiar with the visit said.