WASHINGTON (Reuters) - The top Democrat on the Senate Foreign Relations Committee on Wednesday urged the Trump administration not to waive or remove sanctions on Russian oligarch Oleg Deripaska or two companies he controls.

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In a letter to U.S. Treasury Secretary Steve Mnuchin, Senator Bob Menendez cited unspecified reports that Treasury was considering such a move and noted the department’s own analysis says the oligarch is accused of crimes from blackmail to murder.

“I see no reason to remove sanctions against Mr. Deripaska, and until he divests from and relinquishes control of Rusal and EN+, there is no justification to remove the sanctions on those companies,” he wrote.

The U.S. Treasury Department last month postponed a Dec. 12 deadline for Deripaska to reduce his holdings in the companies, giving the Russian tycoon until Jan. 7.

Treasury in April imposed the sanctions 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.

Deripaska was one of 24 Russians - allies of President Vladimir Putin - slapped with sanctions in one of Washington’s most aggressive moves to punish Moscow for its alleged interference in the 2016 U.S. presidential election and other “malign activity.”

Russian election-related activities, including any coordination with the campaign of then-candidate Donald Trump, are being investigated by a federal special counsel.

In his letter, Menendez outlined Deripaska’s close ties with the Kremlin and said changes to the sanctions would meet with strong opposition in Congress.

Rusal is the world’s largest aluminum producer outside China.

“The goal is not to put EN+ or Rusal out of business given the global implications for the aluminum industry and the potential impact on our close allies in Europe,” Menendez said.

But the Treasury Department must ensure that Deripaska relinquishes his control of both entities and no longer benefits from them, he said.

“Putin’s aggression against us and our allies cannot go unchecked,” Menendez said. How Treasury handles Deripaska and his companies “exercise will shape our perceptions about the Administration’s seriousness in implementing the Russia sanctions regime.”

The federal government was closed on Wednesday for the funeral of former President George H.W. Bush and a Treasury spokesman did not return a call seeking comment.