FILE PHOTO: President of En+ Group, Oleg Deripaska attends an agreement signing ceremony with the Krasnoyarsk region's government, in Moscow, Russia December 12, 2017. REUTERS/Sergei Karpukhin/File Photo

HONG KONG (Reuters) - Russia’s largest aluminum producer Rusal said on Monday it has not received a formal resignation from director Oleg Deripaska, and reiterated that its business and prospects may be affected by U.S. sanctions.

Washington imposed sweeping sanctions last month on some of Russia’s biggest companies and businessmen, including En+ Group Plc, striking at allies of President Vladimir Putin to punish Moscow for alleged meddling in the 2016 U.S. presidential election and other so-called malign activities.

Rusal noted in a statement that its controlling shareholder, Russia’s En+, said last week that Deripaska had resigned from its board of directors, in a move that could help alleviate sanctions pressure on the firm.

En+ also announced its directors had endorsed its chairman’s plan to have sanctions lifted.

“The company reiterates that its current assessment is that it is still highly likely that the impact may be materially adverse to the business and prospects of the group,” Rusal said in a filing to the Hong Kong bourse.

“As at the date of this announcement, the company has not received any formal resignation from Mr. Deripaska.”

Rusal shares in Hong Kong, which slumped in April on news of the sanctions, were trading up six percent at 0310 GMT.