About 60 charities, churches and other tax-exempt groups are being investigated for possibly breaking federal rules that bar them from participating in political activities, the Internal Revenue Service said yesterday. Such violations would threaten their tax-exempt status, the IRS said.

The investigations involve guidelines for 501(c)(3) groups, which are granted tax-exempt status so long as they do not participate in political activities such as endorsing candidates or making campaign donations.

Under the law, the IRS cannot reveal names from or details of its investigations. It did disclose that about 20 of the groups being investigated are churches.

Heightened concerns about improper political activities in this election season warranted the creation of a committee of career civil servants to look into potential political violations by tax-exempt groups, according to the agency. Of more than 100 reports received during the past couple of months, that committee found 60 cases that merited further scrutiny, the IRS said.

"Our obligation is to enforce the law, which prohibits all charities from engaging in political activities," IRS Commissioner Mark W. Everson said in a statement.

The disclosure from the IRS came a day after Julian Bond, the chairman of the NAACP, said that the IRS started investigating his group after he criticized President Bush. Documents released on Thursday by the Baltimore-based organization said that IRS agents are investigating Bond's July 11 keynote address in Philadelphia at the NAACP's annual convention.

An "Information Document Request" from the IRS said Bond in his remarks "condemned the administration policies of George W. Bush on education, the economy and the war in Iraq."

Bond contends that the timing of the inquiry gives the appearance that it is politically motivated, a charge the IRS denied.

"What seems enormously outrageous to us are the facts that condemnation and criticism are reasons that we should lose our tax exemption," Bond said in a conference call yesterday. He maintained that the speech was nonpartisan even though it was critical of Bush.

Democratic presidential candidate John F. Kerry asked the Justice Department's civil rights division to conduct its own investigation of the IRS actions.

"If the timing of this process leads some to believe politics is at play, it could have a chilling impact on African Americans' participation in the American political process," Kerry said in a letter yesterday to Assistant Attorney General R. Alexander Acosta.

An IRS "fact sheet" provided by the agency noted: "Even activities that encourage people to vote for or against a particular candidate on the basis of nonpartisan criteria violate the political campaign prohibition."