D.C. Council Chairman Kwame R. Brown asked city ethics officials Thursday to delay a decision on whether to penalize his 2008 reelection campaign for financial wrongdoing while federal prosecutors probe the issue.

The Board of Elections and Ethics agreed to ask U.S. Attorney Ronald C. Machen Jr. to investigate, indefinitely delaying a deeper airing of the allegations and a potential levy of large fines.

“It means we think there’s criminal activity here that needs to be looked into,” said the board’s chairman, Togo D. West Jr.

But prosecutors and a campaign finance official said Thursday that the allegations against Brown’s campaign are already under review, making the Democrat the fourth sitting elected city official to be subject to federal scrutiny.

William Miller, a spokesman for Machen, said his office was “aware” of the board’s referral and “will take the information it provides into account as we continue to review this matter.” An attorney for the city’s Office of Campaign Finance, William O. SanFord, told the board that federal investigators had visited the office and had taken records pertaining to Brown’s case.

An audit released in April by campaign finance officials found that Brown’s 2008 campaign, for a second term as an at-large council member, failed to report contributions and expenditures totaling more than $270,000.

The audit also found that the campaign passed $239,000 to a company owned by Brown’s brother, Che Brown, via a now-defunct consulting firm. A subsequent complaint filed by the campaign finance office alleged that Brown’s campaign had failed to register a $60,000 bank account that Che Brown controlled.

In brief remarks after leading a council hearing Thursday, Brown said he is “looking forward to moving forward and getting some closure.”

“I’m looking forward to a full investigation,” said Brown, who has characterized the alleged irregularities as “administrative errors.”

A statement attributed to Brown’s 2008 campaign committee and distributed by his council staff said that the direct referral to federal authorities is “the most efficient course for this matter to follow.”

It added that the campaign is “confident that such an investigation will not find any criminal wrongdoing by the committee, or those acting on behalf of the committee.”

Che Brown referred questions to his attorney, A. Scott Bolden. “He’s cooperating with the investigation and has nothing to hide,” Bolden said.

Several of the chairman’s council colleagues declined to address his handling of the campaign finance matter.

Vincent B. Orange Sr. (D-At Large), who raised questions about Brown’s past fundraising while running against him for the chairmanship last year, said asking for the federal referral was a “good legal strategy.” He noted that the decision defers any penalties until Machen reaches a finding.

“It always appeared that the U.S. attorney was going to be the final arbiter,” Orange said. “We’ll wait and see.”

The Board of Elections and Ethics is empowered to assess fines for civil violations of campaign finance law after a public hearing process. But Frederick D. Cooke Jr., representing Brown’s campaign, asked the board to allow federal authorities to investigate first “as a matter of efficiency and expedition.”

The federal review, however, will take place outside the public eye.

Cooke noted that any criminal investigation, or the potential for a criminal investigation, would probably lead witnesses to invoke their Fifth Amendment right against self-incrimination.

“Our view is, let’s just cut to the chase,” Cooke told the board.

West was receptive to Cooke’s suggestion. “The U.S. attorney’s got the FBI; they can do this job quicker,” West said, noting that federal authorities have “much more firepower than we do.” He said the board reserves the right to take action after the federal probe concludes.

Kenneth McGhie, a board attorney, said a violation of campaign law must be “willful” to rise to a criminal offense. The board has previously referred at least two cases to the U.S. attorney’s office — a 2002 finding of petition fraud in then-Mayor Anthony A. Williams’s (D) reelection campaign, and a 2004 finding of petition fraud related to an effort to place a gambling initiative on the ballot. Neither case resulted in criminal charges.

West would not establish a time frame for proceeding with the board’s own sanctions after referring the case. “We can’t put deadlines on the U.S. attorney, but we have to respect our own responsibilities and jurisdiction,” he said.

Federal prosecutors have not charged a sitting D.C. elected official since Marion Barry’s 1990 arrest as mayor on drug charges. But recent months have seen a spate of investigations.

Allegations leveled by minor mayoral candidate Sulaimon Brown have led to an active probe of Mayor Vincent C. Gray’s 2010 election campaign. An investigation by the city’s attorney general resulted in graft allegations against council member Harry Thomas Jr. (D-Ward 5), which have been referred to Machen. And a long-running probe into the city taxicab industry led to the conviction of an aide to council member Jim Graham (D-Ward 1) on felony corruption charges. Graham has not been charged.

In neighboring Prince George’s County, a federal investigation into public corruption has led to guilty pleas from former county executive Jack B. Johnson (D) and wife, Leslie Johnson (D), who has agreed to resign her County Council seat at the end of the month.

Paul Craney, executive director of the D.C. Republican Committee and a frequent critic on ethical matters in city government, said he was pleased that Brown has asked for a federal review.

“He’s making the best of a situation that’s not looking good for him right now,” Craney said. “Any time a U.S. attorney looks into something, it becomes very serious.”