WASHINGTON (Reuters) - The United States on Friday said it was postponing the enforcement of sanctions on Russian companies EN+ <ENPLq.L >, Rusal and Gaz PAO for nearly four weeks as their top shareholder works on a plan to cut his stakes.

FILE PHOTO: Russian aluminium tycoon Oleg Deripaska waits before the talks of Russian President Vladimir Putin with South Korean President Moon Jae-in at the Kremlin in Moscow, Russia June 22, 2018. REUTERS/Sergei Karpukhin/File Photo

The U.S. Treasury Department had given Russian tycoon Oleg Deripaska until Dec. 12 to reduce his holdings in the three companies but said in a statement that the deadline had been moved to Jan. 7, 2019.

“EN+, RUSAL, and GAZ are proposing substantial corporate governance changes that could potentially result in significant changes in control of these sanctioned entities,” Treasury said in a statement explaining why the deadline was postponed.

Rusal, En+ and GAZ declined to comment.

The U.S. Treasury imposed the sanctions in April on Deripaska and several companies in which he is a large shareholder, citing “malign activities” by Russia, as well as allegations of past crimes by Deripaska himself.

The sanctions, the toughest since Moscow’s 2014 annexation of Crimea, have been postponed several times as the U.S. considers plans by Deripaska to divest shares in the companies so that he no longer controls them, among other moves.

Rusal and its parent En+ Group have recruited directors and management not linked to Deripaska in recent months as part of talks with Washington over easing U.S. sanctions.

Rusal named Evgenii Nikitin, who has been acting chief executive since May and previously headed its aluminum division, as its CEO last Friday. En+ also appointed a new CEO.

Friday’s move extends licenses relating to the sanctioned firms to authorize activities needed to wind down operations or contracts, according to a statement on the U.S. Treasury Department’s website. It also extends licenses to authorize transactions needed to divest debt, equity and other holdings.

Concerns over the impact of sanctions on Rusal have roiled aluminum markets. Rusal is the world’s second-biggest producer after China’s Hongqiao. Japan’s top aluminum rolling company, UACJ Corp, said on Nov. 1 that it was removing Rusal from its 2019 suppliers list due to uncertainty over the sanctions.