One of the "527" groups that raised money for TV ads attacking Philadelphia mayoral candidate Tom Knox disclosed its financial backers yesterday - and two of its three donors were labor unions that have endorsed Knox rival Bob Brady.

Alex Z. Talmadge Jr., founder of the group, the Economic Justice Coalition for Truth, insisted yesterday that his group had no ties to Brady.

"I did not ask them who they had endorsed," Talmadge said, referring to the unions. "That's none of our business."

A second "527" group, which calls itself Working People for Truth and gives a Washington address, still is not naming its backers.

Unlike the Economic Justice group, it did not file a campaign report yesterday. It sent a letter to the city Board of Ethics asserting that it is a "a creature of federal statute" and not governed by Pennsylvania law.

The letter, from Washington lawyer Donald R. Dinan, added: "Kindly consider this a formal request for an advisory opinion as to whether the [ethics] commission believes a report is required."

The group is a so-called 527 organization, a term taken from the section of the Internal Revenue Code that governs them. While a new city law limits campaign donations, 527s may raise and spend freely as long they are not coordinating their efforts with any candidate.

Under state law, all groups spending money to "influence the outcome" of elections - in this instance, the city's May 15 primary - had to file reports by yesterday's deadline, according to Timothy A. Dowling, an official with the City Commissioners, who help enforce the state law.

Dowling said the Working People organization should have filed and might face a fine for failing to do so.

Robert Bedard, who has been serving as the group's spokesman, said he would have no comment beyond Dinan's letter.

The Working People group paid about $65,000 for TV spots last weekend that said Knox was a fake.

As for the Economic Justice group, it reported raising $64,500, saying the money came from three union sources:

$50,000 from a political fund of the Philadelphia Federation of Teachers. Under the city's election law, such funds can only give $20,000 to any one candidate. But this cap does not apply to a 527 group.

$7,500 from the political fund of Iron Workers Local 401.

$7,000 from the Sprinkler Fitters Local 629 political fund.

The Sprinklers and the Iron Workers locals have endorsed Brady for mayor. Brady has denied any link to either of the 527 groups.

Ted Kirsch, PFT president, declined yesterday to say who had asked his union's fund to help Talmadge's group - except to say it was not Talmadge. "We had a request," Kirsch said. "I can't say who it came from."

Kirsch said the PFT had donated to every mayoral candidate except Knox. On a vote of its members, the PFT decided this year against endorsing any candidate.

While the Economic Justice Coalition has raised money for TV ads, it has not succeeded in airing any. 6ABC initially agreed to show the group's anti-Knox ad, but later refused, as did NBC10 and CBS3. The stations did so after a lawyer for Knox warned that he might sue them. Lawyer Paul R. Rosen said the Talmadge group was illegal and its ad a smear.

The anti-Knox ad in question was produced by Ken Smukler, a former adviser to Brady. Smukler said he made the ad after he quit the Brady campaign April 27 - an exit prompted by news that Smukler had talked with Talmadge and others about launching a 527 group.

Talmadge and Smukler complained that the Knox campaign violated their free-speech rights by pressing the stations not to show the ad. Rosen denied this.

The filing yesterday may be the last from Talmadge's group, though he said yesterday it was still raising money.

The candidates are bound by a state law that says that after yesterday's deadline for campaign reports, they must report any further pre-primary donations immediately.

But Talmadge said his 527 group was not bound by that law and that he would not release donors' names voluntarily. If he did, he said, reporters would try to talk to them.

Contact staff writer Craig R. McCoy at 215-854-4821 or cmccoy@phillynews.com.

Inquirer staff writer Dylan Purcell contributed to this article.