The AP reported there was a $10 million annual contract between Manafort and aluminum magnate Oleg Deripaska that is believed to have started in June 2006. The business relationship lasted until 2009, the AP said, citing a source.
That timeframe would mean the contract ended well before Manafort became officially connected to Donald Trump's presidential campaign in the spring of 2016.
Manafort denied any wrongdoing and said that his work with the oligarch did not relate to Putin or his government.
"I worked with Oleg Deripaska almost a decade ago representing him on business and personal matters in countries where he had investments," Manafort told ABC News today. "My work for Mr. Deripaska did not involve representing Russian political interests."
A senior White House official told ABC News not to expect any comment from the White House on the new AP report.
The AP report alleges that Manafort proposed a confidential strategic plan that suggested he would influence politics, business dealings and media coverage within the United States and elsewhere to benefit the Putin government.
Questions about Manafort's connections to Russia have been raised since August of 2016 when he resigned as the Trump campaign chairman, and have continued to come up as recently as this week.
Manafort's name was mentioned multiple times when FBI director James Comey spoke at a House Intelligence Committee hearing Monday where he revealed that the agency is investigating Russian interference into the U.S. presidential election and possible involvement of Trump associates.
The Trump administration has already started distancing itself from Manafort. At the White House press briefing Monday, press secretary Sean Spicer downplayed Manafort's involvement in the campaign, saying that he "played a very limited role for a very limited amount of time."
Manafort was named Trump campaign chairman in April and resigned in August 2016, and one of his biggest tasks was running the Republican National Convention.
ABC News’ John Santucci and Jordyn Phelps contributed to this report.