WNET, the New York City public television broadcaster, said on Friday that it would return a $3.5 million grant it received to sponsor an ambitious project on public pensions in the face of charges that it solicited inappropriate underwriting for the series.

In the absence of the funding from the Laura and John Arnold Foundation, the project, called “Pension Peril,” will go on hiatus, although WNET will continue to report on the topic. The series, which began in September, was examining the economic sustainability of public pensions.

Earlier, after a critical report on Wednesday by David Sirota on the website PandoDaily, WNET officials said they were comfortable with the foundation’s funding. Mr. Sirota sharply criticized WNET for accepting the Arnold Foundation money because John Arnold, a former hedge fund manager, has financially backed efforts to persuade municipalities to cut public employee pension benefits. On its website, the foundation said that for three years it “has encouraged governments to face the true magnitude of their pension problems and to develop structural reforms that are comprehensive, sustainable and fair.”

In a joint statement from PBS and WNET, PBS said it stood by WNET’s reporting in the series but “in order to eliminate any perception on the part of the public, our viewers and donors that the foundation’s interests influenced the editorial integrity of the reporting for this program,” WNET would return the gift.