Russia's second-largest bank said it has halted lending to Russian billionaire Oleg Deripaska following U.S. sanctions against the oligarch.

"Of course, we are not lending any new money to him, we are not having any operations with him," Andrei Kostin, the president of VTB Bank told CNBC's Geoff Cutmore.

He said the bank is waiting to see what the U.S. Office of Foreign Assets Control (OFAC), which administers economic sanctions, does next. The United States in April slapped sanctions on a group of Russians including Deripaska, who has since announced plans to quit his post as director of aluminum giant Rusal.

"With Rusal and others, we're waiting for the OFAC decisions, but we hope that the issue will be resolved because we are a big creditor to him so we need to return our money," he said, insisting that the bank's business would not be affected.

"The business with newly sanctioned institutions represents less than 2 percent of our assets so of course it will affect us to a certain extent but we still have to see what's going to happen with them as there's some discussion that they could be lifted for Rusal and some other companies. So we shall see, but at the moment it doesn't represent a huge problem for us," he said.

Deripaska quit the EN+ board (Rusal's parent company) a few days ago and said he would reduce his majority stake in the company to below 50 percent in a bid to reduce pressure on the company and its subsidiary — both of which were listed on the "oligarch-owned companies" list under the new U.S. sanctions.

He also said he would quit the board of Rusal, although on Monday the firm said it had not yet received a formal resignation, Reuters reported.

Deripaska's attempt to distance himself from those companies comes after the U.S. decision to impose sanctions on the aluminum firm and other companies in which the Russian billionaire is a major shareholder.

Speaking on oligarchs like Deripaska, Treasury Secretary Steven Mnuchin said in a damning statement in April that this was punishment for alleged Moscow meddling in the U.S. election and other "malign activity."