Akhmetov is one of the richest men in Ukraine and bankrolled the Party of Regions, a Ukrainian political party aligned with Moscow that Manafort worked to bolster.
The accusation could be important evidence in Mueller's ongoing probe into potential coordination between the Trump campaign and the Kremlin. On the eve of a second trial in Washington, D.C., the next month Manafort struck a plea deal with prosecutors. he agreed to fully cooperate with prosecutors and plead guilty to two counts of conspiracy in a separate case in Washington, D.C.
Those details, as well as an exchange between Manafort and an unidentified person who was looking for an introduction with Trump, were not publicly known until Tuesday, when Manafort's attorneys put them into a court filing that was supposed to be redacted.
Another witness, testifying against Manafort under oath, said Manafort and Akhmetov "knew each other well". He entered a plea agreement with special counsel Robert Mueller on September 14, 2018, but prosecutors have since alleged that Manafort has violated the terms of the deal by lying about certain topics. They since confirmed that he was interviewed by Mueller's team.
Paul Manafort arrives for a hearing at US District Court on June 15, 2018 in Washington. The U.S. and European Union have imposed sanctions on Russian Federation over that move as well as the country's support for separatist rebels in eastern Ukraine.
Manafort earned millions from his Ukrainian political work over several years.
Prosecutors have also accused Manafort of lying about his contacts with Trump administration officials, which defense lawyers deny.
A statement to CNN on behalf of Akmetov said: "Mr. Akhmetov never requested nor received any polling data or any other information about the 2016 USA elections from Paul Manafort or Konstantin Kilimnik".
He referred Reuters to Schiff's statement that lawmakers on the committee "need to find out" about Manafort's interaction with Kilimnik on polling data. Manafort denied that he was trying to hide the meetings he had with Kilimnik, who has also been charged in Mueller's wide-ranging investigation, and instead had just forgotten about them until he'd been presented evidence to refresh his memory.