Federal agents raided the home and offices Friday of a top District government contractor and political donor as a part of an investigation into city corruption, officials familiar with the probe said.

The officials, who spoke on the condition of anonymity because they were not authorized to speak publicly about the raid, identified the contractor as Jeffrey E. Thompson, the owner of Chartered Health Plan, the city’s single-largest contractor.

A spokesman for the U.S. attorney’s office in the District would only confirm “law enforcement activities.” The spokesman, William Miller, said that no arrests were made and that no charges were filed.

At 8 p.m. Friday, a sedan bearing an Internal Revenue Service placard and a sport-utility vehicle with emergency lights were parked outside a building on 15th Street NW, where Thompson keeps offices.

Attorney General Irvin B. Nathan on Friday was ordered by the U.S. attorney’s office to preserve all documents related to Chartered Health, according to a city government official who also spoke on the condition of anonymity because he was not authorized to speak publicly.

Thompson did not return messages left at his home and office Friday evening. The officials who spoke about the probe did not allege that Thompson broke any laws.

Friday’s actions are the latest indication that federal authorities continue to investigate corruption in city government. Nearly two months ago, Harry Thomas Jr., who represented Ward 5 on the D.C. Council, resigned just before pleading guilty to felony charges related to the theft of $353,000 in taxpayer funds intended for children. Also, a federal probe into Mayor Vincent C. Gray’s 2010 campaign fundraising continues.

There are few elected officials in the city who have not taken donations from Thompson and — in many cases — his partners, companies and employees. He has helped raise tens of thousands of dollars for political candidates, including Democratic mayors Gray, Adrian M. Fenty and Anthony A. Williams. He has personally contributed more than $200,000 to federal campaigns and committees.

Thompson is the majority owner of the city’s single-largest contractor, Chartered Health, which holds a Medicaid managed-care contract worth as much as $322 million yearly. The company has held the contract for more than a decade.

He is also the co-founder of a prominent accounting firm — Thompson, Cobb, Bazilio & Associates — that has done work for the city dating back two decades. One of the nation’s largest minority-owned accounting firms, it has also done extensive work for federal agencies.

Williams called Thompson, a 57-year-old self-made businessman, “the consummate Washington guy” in a Washington Post profile in July. “He knows how to get things done,” he said. Thompson is also a noted philanthropist, with particularly long-standing ties to the National Council of Negro Women.

In July, The Post found that the Gray campaign had an unusual practice of accepting cash donations and turning the cash into money orders, often over the legal limit.

According to campaign finance reports, several large money orders — from $500 to $2,000 — were contributed by Thompson’s firms or by relatives of employees or people with ties to Thompson. All contributors contacted by The Post declined to comment then.

In recent weeks, officials with knowledge of the grand jury probe into Gray’s campaign said investigators were beginning to focus on independent expenditures, particularly those from registered and possibly unregistered committees that allegedly collaborated with the campaign.

According to one person with knowledge of the Gray campaign, the mayor was reluctant in 2010 to use Thompson to help bankroll his campaign. But Gray softened after a meeting that was brokered by Reuben O. Charles II, who had a key role in Gray’s fundraising.

After raising thousands in the 2010 mayoral campaign and a D.C. Council special election last year, there is no indication that Thompson has donated to any election campaign this cycle.

Staff writer Tim Craig contributed to this report.