Paul Manafort was in debt by as much as $17 million to pro-Russia interests before he joined the Trump campaign in March 2016, according to a report Wednesday.
The New York Times obtained financial records filed last year in Cyprus, where Manafort kept bank accounts during his time working in Ukraine and investing with a Russian oligarch.
The Times says the debt appears to be owed by shell companies tied to Manafort's business pursuits in Ukraine when he worked as a consultant to the pro-Russia Party of Regions.
In 2015, the Russian oligarch Oleg Deripaska filed a complaint in a court in Virginia claiming Manafort and his partners owed him $19 million related to a failed investment in a Ukrainian cable television business.
A spokesman for Manafort, Jason Maloni, denied his client owes money to Russian interests.
"Manafort is not indebted to Mr. Deripaska or the Party of Regions, nor was he at the time he began working for the Trump campaign," Maloni told the Times. "The broader point, which Mr. Manafort has maintained from the beginning, is that he did not collude with the Russian government to influence the 2016 election."
Manafort resigned as Trump's campaign manager last August while concerns mounted over his past work in Ukraine.
He is known to be a focus of investigations by Congress and special counsel Robert Mueller into Russia's interference in the 2016 election and possible Trump campaign ties to Russia.
He participated in a meeting last June with a Russian attorney promising damaging information on Hillary Clinton, the Democratic nominee for president.
The Senate Judiciary Committee has invited Manafort to testify in a public hearing on Wednesday, July 26. He has not yet confirmed the invitation.