The FBI is looking at suspicious wire transfers that authorities say are linked to President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE's former campaign chairman, Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE, according to a BuzzFeed News report.

The series of at least 13 wire transfers from offshore companies between 2012 and 2013 were initially flagged by U.S. financial institutions, which are required to identify suspicious transactions, the news outlet said.

BuzzFeed, citing law enforcement sources, reported that the companies did not specify what the money was for. The transactions originated in countries known for money laundering and much of the funds eventually ended up in the U.S., it added.

ADVERTISEMENT

Suspicious activity reports do not prove improper or illegal activity, and financial institutions are required to flag cash transactions that exceed $10,000 in a single day, even if the transactions do not seem suspicious, the news outlet said.

The transactions, which reportedly have been on federal law enforcement officials' radar since 2012, totaled millions of dollars.

The FBI's investigation into Manafort "lay dormant" for a while, according to BuzzFeed.

But the Treasury Department's Financial Crimes Enforcement Network uncovered its previous reports on Manafort and forwarded them to the FBI's International Corruption Unit, whose agents were working with special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE on his investigation into Russian election meddling, it added.

Manafort has become a central figure in Mueller's investigation, which has expanded to look at possible financial crimes by Trump campaign officials. In July, the FBI conducted an early morning raid on Manafort's northern Virginia home, and Mueller has since subpoenaed the former Trump campaign chairman's spokesman and former attorney.

Manafort was forced out as Trump's campaign chairman in August 2016 after he came under scrutiny for his past lobbying work for pro-Russian Ukrainian oligarchs.