WASHINGTON - An investment fund for philanthropist Rachel Mellon contributed $495,000 to a labor-backed group that is running ads in Iowa in support of Democrat John Edwards' presidential campaign.

A Federal Election Commission filing by the Alliance for a New America reported the donation from Oak Spring Farms LLC, the corporate entity that holds Mellon's fortune. Mellon is the 97-year-old widow of philanthropist Paul Mellon, the son of industrialist Andrew Mellon.

Rachel Mellon contributed the maximum $4,600 allowed to Edwards' campaign earlier this year.

Alexander Forger, a lawyer listed in New York city property records as holding power of attorney for Mellon, lists himself in FEC records as director of Oak Springs Farm LLC. He also has contributed the maximum $4,600 allowed to Edwards' campaign.

Oak Spring Farm LLC contributed $250,000 last year to a nonprofit political group that Edwards set up called One America.

Forger did not immediately respond to e-mail and telephone messages.

Both One America and the Alliance for a New America are "527" corporations, nonprofit groups that can carry out some political activity but have come under scrutiny by the FEC for their advertising during past presidential campaigns. They derive their name, "527," from the section of the IRS code that authorizes them.

The Alliance for a New America is a newly created organization headed by former Edwards adviser Nick Baldick. It has received most of its support from labor groups, many of them locals belonging to the Service Employees International Union. The alliance is spending about $600,000 on radio ads and about $750,000 on television ads in Iowa supporting Edwards.

Edwards is also getting support from another 527 group, Working for Working Americans, that is financed by the United Brotherhood of Carpenters and Joiners and is running television ads supporting Edwards in Iowa.

Such groups are not allowed to coordinate their efforts with a political campaign. Edwards aides have said there has been no such coordination, and Edwards himself has called on the 527 to stop its activities. But in an interview on Radio Iowa Thursday, Edwards also said he was proud of the support from the SEIU, carpenters and steel workers unions that are backing him.

"There are some things that when a union supports you can work with them on and some things that you can't, and we have been absolutely in complete compliance with the law, both the letter and the spirit of the law," he said.

Dave Regan, president of SEIU District 1199, one of the groups financing the Alliance for a New America, said:

"We are pleased to help support this organization and have allies who believe that issues like universal health care, the well-being of the middle-class and a strong economy warrant a positive discussion."