The special counsel investigating Russian involvement in the 2016 election is looking at Democratic lobbyist Tony Podesta, the brother of Hillary Clinton’s presidential campaign manager, NBC reported Monday. ​

The probe into Podesta and his firm, the Podesta Group, grew out of Robert Mueller’s examination of the finances of Paul Manafort, Donald Trump’s former campaign manager, NBC reported, citing sources.

Manafort created a public relations campaign, which ran between 2012 and 2014, for the nonprofit European Centre for Modern Ukraine and hired a number of companies to work on it — including Podesta’s.

The campaign promoted Ukraine’s image in the West and was backed by the Party of Regions, a pro-Russian political party once run by former Ukrainian President Viktor Yanukovych, a client of Manafort.

He fled Ukraine in 2014.

Mueller initially was looking into the ECMU and Manafort as part of a fact-finding mission but expanded it into a criminal inquiry to determine whether Podesta’s firm violated the Foreign Agents Registration Act, the network reported.

The law requires people or companies that lobby on behalf of foreign governments, leaders or political parties to disclose their spending and activities to the Justice Department. Violations are a felony that can lead to prison sentences of up to five years.

The Podesta group filed a FARA registration only after reports surfaced in the media about its work for ECMU.

​John Podesta, Clinton’s ​ex-​campaign manager, is not affiliated with his brother’s company and is not part of the Mueller probe, the report said.

The company is “cooperating fully with the Special Counsel’s office and has taken every possible step to provide documentation that confirms timely compliance​,” a spokesman said in a statement to NBC. “​In all of our client engagements, the Podesta Group conducts due diligence and consults with appropriate legal experts to ensure compliance with disclosure regulations at all times — and we did so in this case.”

​Manafort has emerged as one of the key players in Mueller’s investigation into Russian meddling in the election.

FBI agents raided his Alexandria, Va., home in July.