The Swiss bank said on Thursday that customers that were not sanctioned would not be affected by its move in the second quarter, which it said "does not represent a freezing of the assets".

"Credit Suisse reclassified certain impacted assets from assets under management to assets under custody," a spokeswoman for the bank said, adding that this had not resulted in a financial loss for the bank.

"We remain highly committed to Russia and continue to monitor developments," she said.

The move by Credit Suisse, which owned aircraft surrendered by Russian tycoon Oleg Deripaska and had lent money to Russian oligarch Viktor Vekselberg before sanctions, underscores a widespread fear among banks of reprisal from Washington.

For Russia's elite, such steps could close off an important avenue for finance as well as a safe haven for billions of rubles of their wealth.

(Reporting By John O'Donnell; Editing by Elaine Hardcastle)