Donald Trump’s one-time presidential campaign chairman Paul Manafort admitted in a court filing Tuesday he provided polling data from the campaign to a Russian with ties to intelligence during the 2016 US presidential race.

Manafort denied allegations from the Russian collusion investigation of Special Counsel Robert Mueller that he had lied about his dealings with Konstantin Kilimnik, arguing he merely forgot details during the hectic election campaign.

The specifics of the Mueller allegations were not previously known publicly, having been blacked out in a heavily redacted December 7 filing by the Russia collusion prosecutor’s team.