Paul Manafort. Chip Somodevilla/Getty Images The FBI is reportedly looking into potential ties Donald Trump's former campaign manager may have had with Russia.

The inquiry apparently stems from alleged foreign business connections Paul Manafort may have had with Russian entities, according to a report published by NBC News on Monday evening.

Manafort, who served as Trump's campaign manager for several months before parting ways with the Republican presidential nominee in August, denied he had any business relationship with the Kremlin, telling NBC that "none of it is true."

"There's no investigation going on by the FBI that I'm aware of," he said.

Current Trump campaign manager Kellyanne Conway, asked about the report on MSNBC Monday night, referred to Manafort's comments.

The New York Times reported in August that a pro-Russian political party in Ukraine advised by Manafort designated $12.7 million in undisclosed cash payments for him between 2007-12. It is unclear what exactly the series of 22 payments designated for Manafort were for.

The FBI's inquiry raises questions about the possibility that Russia may be attempting to influence the US presidential election. Those concerns have been amplified by Trump's foreign policy rhetoric that some observers say is curiously favorable to Russia and its president, Vladimir Putin. The US intelligence community has accused the Russian government of being behind hacks of Democratic Party organizations this year.

The FBI's inquiry has not yet developed into a full-fledged criminal investigation, NBC News said, and it was unclear whether or not that would happen.

News of the inquiry comes as FBI Director James Comey is being jostled by both Republican and Democratic leaders over his handling of the investigation into Hillary Clinton's private email server from her time as secretary of state. The FBI's move to rekindle that investigation was largely seen as potentially damaging to the Democratic nominee's White House bid.

Clinton on Monday apologized for her use of the private server, as she has done before, and claimed the FBI had "no case" against her.

Natasha Bertrand contributed reporting.