Philadelphia ? Federal law enforcement officials on Wednesday confirmed that listening devices found in the offices of Mayor John F. Street were planted by the FBI — a discovery that touched off a political furor just weeks before Election Day.

Three federal law enforcement officials, speaking on condition of anonymity, acknowledged that the FBI was responsible for the bug, but refused to comment on whether the Democratic mayor was a target of an investigation or to provide any details about the nature of the probe.

Pennsylvania Gov. Ed Rendell, a Democrat, and Sen. Arlen Specter, a Republican, were among several politicians who called on the FBI Wednesday to tell the public what it knows about the eavesdropping equipment, found Tuesday.

“I think given this extraordinary situation with four weeks to go in the campaign, it is incumbent upon the FBI to say why they planted the device,” Rendell said.

The bug was found during a routine sweep of Street’s office by police. Street is locked in a bitter rematch against Republican businessman Sam Katz, and the campaign has been marked by charges of threats and race-baiting. Election Day is Nov. 4.

At a meeting with reporters Wednesday, Street said for the second day that he didn’t know who bugged his office or why.

“I haven’t done anything wrong, and I don’t know that anybody in my Cabinet or in my staff around me has done anything wrong,” Street said.

Street’s campaign suggested the bugging was instigated by the U.S. Justice Department for political reasons.

“The timing of the discovery of these listening devices seems incredibly strange, seeing that we are four weeks out of the election, and we have a Democratic mayor ahead in the polls, and we are on the eve of the first mayoral debate,” Street campaign spokesman Frank Keel said.

“Do we believe that the Republican Party, both at the federal level and state level, is pulling out every stop to get Pennsylvania in 2004? Absolutely,” Keel said. “Is the Republican Party capable of dirty tricks? I think that is well-documented.”

U.S. Atty. Patrick Meehan, the top federal prosecutor in Philadelphia, declined to say what federal agents might know about the bug but denied politics played any role in his office’s decisions.

Katz called the discovery “breathtakingly shocking.” His campaign denied any role.