It's too late for the information to help voters with their choices, but another of the "527" organizations that attacked mayoral candidate Tom Knox has revealed its financing - and it turns out the group got key support from allies of Knox rival Bob Brady.

The painters' union gave $100,000 to the organization, which called itself Working People for Truth, according to information the 527 group sent to the city the day after Tuesday's primary.

The group also got a substantial donation - $25,000 - from the political fund of former State Treasurer Barbara Hafer, records show. The money was not spent, however.

"I was supporting Bob Brady and that's how I got involved," Hafer said last night. She declined to name the person who asked her for the donation.

At first, Hafer said a supporter of Brady, a congressman and the boss of the city Democratic Party, asked her to give. "The Brady campaign, as far as I know, was soliciting money," she said.

Later in the interview, she backed off that statement, saying she was unsure which candidate the caller had backed.

Under city and federal regulation, 527 groups may not coordinate with political campaigns.

In the final weeks of the campaign, Working People for Truth paid for television ads that castigated Knox, a millionaire businessman who financed his own campaign, as an enemy of working people and labeled him a "fake."

The group's spokesman, Robert Bedard, maintained last night that the group had no connection to the Brady campaign.

Kate Philips, who served as Brady's spokeswoman during his unsuccessful campaign, also reiterated yesterday that Brady had nothing to do with the Working People group.

"We have no control over any union contributions," she said. "If they contributed to something, then God bless them. We had nothing to do with it."

Working People for Truth did not disclose its finances before the May 15 primary.

It did so this week after city officials demanded a report. Officials yesterday said they planned to fine the group $150. Bedard said he had no knowledge of such a fine.

Critics, such as the election watchdog group Committee of Seventy, said Working People and other 527 groups abused the primary process.

While a new city law limits campaign donations, 527s may raise and spend freely as long they are not affiliated with with any candidate.

Analysts said the groups - named after a section of the tax code that governs them - gave donors a chance to stage an end-run around the donation limits and launch secretive attacks.

Under the new law, political funds could only give $20,000 a year per election to mayoral candidates.

The gift from Hafer's fund exceeded that figure by $5,000, while the $100,000 from the International Union of Painters and Allied Trades was five times the limit.

The Philadelphia-area District Council 21 for the painters union endorsed Brady for mayor and its political fund gave Brady's campaign $15,000 this year and $5,000 last year. (It also gave Tuesday's Democratic winner, Michael Nutter, a single contribution, $2,500, in 2006.)

Its Washington-based political action committee maxed out with its contributions to Brady, giving him $20,000 this year and $20,000 last year, records show. It has plenty of money to give; records show it had $1.2 million in the bank as of Jan. 31.

Another 527 group that targeted Knox previously revealed its finances. This group, which called itself the Economic Justice Coalition for Truth, disclosed before the primary that donors included two other labor unions that formally endorsed Brady.

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

Inquirer staff writer Andrew Maykuth contributed to this article.