VTB had financed the purchase of a 6.25 percent stake in En+ by Singapore's AnAn Group. Shares in En+ plummeted after Deripaska and his main businesses were included on a U.S. sanctions blacklist.

Speaking on the sidelines of the St Petersburg economic forum, VTB First Deputy CEO Yuri Soloviev said that after the margin call the bank became the owner of the stake in En+ previously held by AnAn.

After the margin call, VTB owns 9.6 percent of En+, Soloviev said.

Singapore's AnAn Group is a strategic partner of China's CEFC, and it had bought a 6.25 percent stake in En+ during the company's London IPO last year.

The bank executive said VTB is also a major creditor of Deripaska’s companies which have been hit by sanctions.

"Our exposure on these (sanctioned) companies of Oleg Deripaska is quite big," Soloviev said. "The current sanctions restrictions are not working against the creditor. We can accept money from these companies and some of them are repaying their debt in a due form."

DERIPASKA'S CONTROL

Washington has said that it would consider removing Deripaska’s main company - aluminium giant Rusal - from the black list if the businessman drops his control over it.

Deripaska controls Rusal via En+ and has already said that he agreed in principal to reduce his stake in En+ to below 50 percent.

Soloviev said that he believed that there was an active dialogue between the U.S. Office of Foreign Assets Control (OFAC) at the level of shareholders and board of directors at Rusal, En+ and Deripaska’s other sanctioned company - Russia's biggest van manufacturer GAZ.

"We as well as the market have the expectations that there is the possibility of these companies' removal from sanctions if the main shareholder reduces his stake to a certain level," he said.

Soloviev said he believed that the Russian government was unlikely to buy part of Deripaska’s stake in En+ and declined to speculate about any other possible buyers. VTB is controlled by the Russian state.

Deripaska's companies also own a number of airports in Russia which may raise a sanctions risk for airlines who pay them landing fees. One of the airports is based in the Black Sea resort of Sochi, which will host part of the World Cup tournament starting in June.

Soloviev said that VTB may consider buying the Sochi airport if the bank receives such a proposal. But there is none yet, he added. VTB previously bought a stake in Deripaska’s airport in Gelendzhik, another Black Sea resort.

The VTB executive said the bank would consider granting financing for Qatar’s planned deal to acquire shares in Russian state oil major Rosneft if it receives such a request.

"It would be great to have such a borrower (Qatar) but we are not in this deal (at the moment)," Soloviev added.

(Reporting by Katya Golubkova and Polina Devitt; Writing by Polina Devitt; Editing by Cynthia Osterman)

By Katya Golubkova and Polina Devitt