(CNN) The Russian oligarch Oleg Deripaska, who at one time had financial ties to Paul Manafort, is suing Treasury Secretary Steven Mnuchin and the US Treasury Department over financial sanctions imposed on him amid a congressional crackdown on Russian interests over meddling in the 2016 presidential election.
Deripaska says in court filings that he's lost $7.5 billion of his net worth since he was sanctioned in early 2018. His remaining businesses are near "the brink of collapse," with banks no longer wanting to lend to him and as he has lost business. The Russian government has also threatened to take over some of his businesses, he said in the complaint.
The Trump administration relaxed sanctions on three of Deripaska's major companies -- Rusal, EN+ Group and JSC EuroSibEnergo -- after changes to their ownership structure, though Democrats in Congress have argued that Deripaska still maintains too much influence over the companies.
A spokesman for the Treasury Department said the agency "does not generally comment on pending litigation" and referred questions to the Justice Department.
In the lawsuit, filed in Washington, DC, federal court, Deripaska accuses the Treasury Department of "using the devastating power of US economic sanctions without adhering to the bounds of its legal authority and in a manner that is inconsistent with the US Constitution."
His firms were swept up as part of more than 200 sanctions imposed on Russian targets by Treasury, including on Rusal, the world's second-largest aluminum producer. The companies spent nearly eight months negotiating with Treasury to significantly reduce Deripaska's influence in order to have sanctions lifted.
Democrats and some Republicans pushed back against the sanctions rollback because of Deripaska's influence in the Russian power and metals industries and for his ties to Vladimir Putin.
In his suit, Deripaska rejected any link to 2016 election issues being investigated by special counsel Robert Mueller.
"There is simply no evidence Deripaska is involved in the Russian government's activities," he said.
Deripaska has longstanding ties to a key figure in the Mueller investigation, Trump's former campaign chairman, Manafort, who was to 7.5 years in prison for conspiracy and other crimes.
Yet Deripaska argued that any suggestion that he was party to Russian efforts to sway the US election in Trump's favor are "nothing more than false rumor and innuendo and originate from decades old defamatory attacks originated by his business competitors."
Court filings in Mueller's investigation showed that when FBI agents searched Manafort's belongings for evidence related to a $10 million loan Deripaska made to Manafort. Manafort allegedly remained in debt to Deripaska for years.
Deripaska has not been charged with any crimes.
This is the second recent lawsuit filed in this court by a Russian over the US government's sanctions.