(Bloomberg) – The US Treasury Department lifted sanctions on three firms tied to Russian tycoon Oleg Deripaska, including United Co. Rusal, a move that will provide relief to the global aluminium market. The metal fell in London.

Deripaska, an ally of Russian leader Vladimir Putin, will remain under U.S. sanctions, and his property will remain blocked. But the Treasury Department is removing restrictions on Rusal, En+ Group Plc and EuroSibEnergo JSC.

“The companies have also agreed to unprecedented transparency for Treasury into their operations by undertaking extensive, ongoing auditing, certification, and reporting requirements. All sanctions on Deripaska continue in force,” the Treasury’s Office of Foreign Assets Control said in a release.

In a separate statement, En+ announced the addition of seven independent directors to its board, as well as a securities swap with Ivan Glasenberg’s Glencore Plc. Under the deal, the London-listed commodity trader will get global depositary receipts representing 10.55% of En+’s enlarged share capital in exchange for its existing 8.75% stake in Rusal.

Rusal said that Chairman Jean-Pierre Thomas had resigned as a director after an “imperative request” from OFAC as a condition for lifting the sanctions. He became chairman in December, replacing Matthias Warnig, a former East German Stasi agent who has known President Putin since at least 1991. Thomas’ appointment drew criticism from American media and some lawmakers during debates in Congress in January because of his calls for investment in the Crimea peninsula, which Russia annexed from Ukraine in 2014, leading to the first round of sanctions. His departure was effective from Jan. 26.

Rusal’s shares rose as much as 6.7% in Hong Kong on Monday, gaining for an eighth straight day.

At En+, new independent directors include Christopher Burnham, the chairman of Cambridge Global Capital LLC, who was a member of Donald Trump’s transition team at the State Department.

Congressional Democrats have tried to block Treasury’s action, citing concerns about the Trump administration’s motives at a time when Special Counsel Robert Mueller is continuing his investigation of Russian interference in the 2016 presidential election and possible connections to the Trump campaign.

“This represents just one more step in undermining the sanctions law, which President Trump has obstructed at every opportunity, while Russian aggression remains unabated,” said Representative Lloyd Doggett, a Texas Democrat.

Aluminium market

Sanctions relief for Rusal, the world’s second-largest aluminium producer, will remove a source of uncertainty from the market. Aluminium surged in April when Treasury announced the financial restrictions, but tumbled in recent months on speculation that the sanctions would be lifted. The price fell on Monday, losing as much as 1.6 percent on the London Metal Exchange.

Deripaska’s agreement with Treasury, negotiated over eight months, includes cutting his direct and indirect share ownership below 50% in each company, overhauling the boards of En+ and Rusal, and providing extensive disclosures, the department said in December when announcing its plans to remove the sanctions.

Rusal is among the largest companies the US has ever put on its sanctions designation list. The value of the aluminium producer declined by more than half from $9.2bn more than eight months ago.

En+ Group is an integrated producer of aluminium and electric power. Its power plants have an aggregated output of 19.7 gigawatts, while aluminium factories (owned through a controlling stake in Rusal) produce 3.9m tonnes of the metal per year.