A watchdog group filed a formal complaint with the Office of Government Ethics over the State Department's treatment of major Clinton Foundation donors just days before news of an FBI investigation into the same issue became public.

The Foundation for Accountability and Civic Trust, a conservative ethics watchdog, filed its complaint Friday after the State Department released a new batch of emails that indicated certain Clinton Foundation insiders had gained heightened access to Clinton when she served as secretary of state.

"It turns out that the FBI was looking into the exact same issue, so it was very interesting," Matthew Whitaker, executive director of FACT, told the Washington Examiner.

FBI agents are reportedly looking into allegations of "public corruption" stemming from the potential overlap of Clinton Foundation and State Department work during Clinton's diplomatic tenure. Fox News first reported the expansion of the FBI probe to include the foundation Monday, and a former U.S. attorney later told the Examiner that aspect of the investigation had begun months ago.

However, Clinton denied reports of the expansion of the FBI probe Monday, calling the Fox News article "unfounded."

"We don't think there's any doubt that there was an ethical violation here," Whitaker said.

The ethics complaint focused on deep-pocketed donors who had made appearances in the latest trove of emails, which the State Department partially published on New Year's Eve and finished releasing early Friday morning.

"Although not a complete list, an example of the donors that obtained special meetings include Bill and Melinda Gates whose family foundation has donated more than $25 million, Victor Pinchuk whose foundation has donated more than $13 million, Susie Buell whose community foundation has donated over $10 million, and Haim Saban whose family foundation has donated more than $10 million, and George Soros who has donated between $500,001 to $1 million, all to the Clinton Foundation through 2015," Whitaker wrote in the complaint.

Kendra Arnold, general counsel for FACT, said the donors cited were selected for more than the size of the checks of they wrote to the Clinton Foundation.

"They each had some issues before the State Department and they were in the last batch of emails," Arnold said.

Questions about the Clinton Foundation's activities while Clinton served as secretary of state first emerged last spring, but were seemingly overshadowed by the controversy surrounding Clinton's use of a private email server to shield her government communications.

The FBI has not commented on reports that agents are investigating potential "public corruption" allegations.