The FBI is investigating whether a Russian banker with close ties to Vladimir Putin funneled money through the National Rifle Association to support Donald Trump’s presidential campaign, it was reported on Thursday.

Foreign contributions to American political campaigns are illegal.

The NRA spent at least $30m to back Trump’s 2016 campaign for president, according to an analysis of public campaign finance records – more than any other outside group, and more than double what it spent to back Mitt Romney’s 2012 campaign.

News outlets have been examining ties and meetings between NRA leaders and Russia for months, including a 2015 NRA delegation to Moscow that included meetings with influential Putin allies.

Thursday’s McClatchy article, which names Alexander Torshin as the banker and NRA ally under scrutiny, is the first to report that links between Russia and the NRA have drawn the attention of federal investigators examining Russia’s attempts to influence the 2016 presidential election. The report cited two unnamed sources, noting that the special counsel Robert Mueller’s investigation into Russian interference is confidential and often focused on classified information.

A spokesman for the NRA did not immediately respond to requests for comment. A Mueller spokesperson declined to comment. The FBI did not immediately respond to a request for comment.

Federal Election Commission regulations not only bar financial contributions from foreign nationals, they also prohibit foreign nationals from “directing, dictating, controlling, or directly or indirectly participating in the decision-making process” of any person or group “with regard to any election-related activities.”

Torshin, the deputy governor of Russia’s central bank and a former member of the Russian parliament, tried in May 2016 to arrange a meeting between Trump and Vladimir Putin, the New York Times reported in late 2017. The overture was rejected by Jared Kushner, the Times reported.

That month, Torshin, Trump, and Donald Trump Jr all attended events at the NRA’s annual meeting in Louisville, the Times reported, where Trump addressed NRA members and the gun rights group formally endorsed him.

A lawyer for Trump Jr said his client and Torshin spoke briefly when they were introduced during a meal at the NRA’s annual meeting.

“It was all gun-related small talk,” the lawyer, Alan Futerfas, told McClatchy.

Congressional investigators reportedly asked Trump Jr about that interaction at a hearing in December.

On Thursday, Everytown for Gun Safety, a gun control group that opposes the NRA’s influence in American politics, called on the NRA to “come clean” about its connections to Russia.