The prestigious Brookings Institution placed its president, retired four-star Marine General John Allen, on administrative leave Wednesday amid a federal investigation into his role in an illegal lobbying campaign on behalf of the wealthy Persian Gulf nation of Qatar.

Brookings' announcement came a day after The Associated Press reported on new court filings that show the FBI recently seized Allen's electronic data as part of the investigation and detailed his behind-the-scenes efforts to help Qatar influence U.S. policy in 2017 when a diplomatic crisis erupted between the gas-rich monarchy and its neighbors.

Allen, who led U.S. and NATO forces in Afghanistan before being tapped to lead Brookings in late 2017, has not been charged with any crimes and has denied any wrongdoing.

Brookings told staffers in an email Wednesday that the institute itself is not under investigation and that the think tank's executive vice president, Ted Gayer, will serve as acting president.

“We have every confidence in the Brookings team's ability to remain focused on delivering quality, independence, and impact," the email said.

The federal investigation involving Allen also has ensnared Richard G. Olson, a former ambassador to the United Arab Emirates and Pakistan who pleaded guilty to federal charges last week, and Imaad Zuberi, a prolific political donor now serving a 12-year prison sentence on corruption charges. Several members of Congress have been interviewed as part of the investigation.

An FBI agent said in an affidavit in support of a search warrant that there was “substantial evidence” that Allen had knowingly broken a foreign lobbying law and had made false statements and withheld “incriminating” documents.

Allen's alleged work for Qatar involved traveling to Qatar and meeting with the country's top officials to offer them advice on how to influence U.S. policy, as well as promoting Qatar's point of view to top White House officials and members of Congress, according to an FBI affidavit in support of a search warrant.

Allen, who was a senior fellow at the Brookings Institution before becoming president, used his official email account at the think tank for some of his Qatar-related communications, the affidavit says.

Qatar has long been one of Brookings' biggest financial backers, though the institution says it has recently stopped taking Qatari funding.

“Brookings has strong policies in place to prohibit donors from directing research activities,” said the email to staffers Wednesday. (AP via VOA

•FILE - Retired Marine General John Allen, then-U.S. special presidential envoy for the global coalition to counter the Islamic State group, speaks during a press conference in Baghdad, Iraq, Jan. 14, 2015.)

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