WASHINGTON —  A filmmaker has sued Sen. John Kerry and a one-time campaign aide, saying they defamed him as they sought to block the broadcast of an anti-Kerry documentary during the 2004 presidential election.

The lawsuit, filed this week on behalf of producer Carlton Sherwood and a Vietnam veterans group, is the latest salvo in the battle over the documentary "Stolen Honor: Wounds That Never Heal."

The film contends that Kerry's anti-war activities when he returned from Vietnam caused further harm to captured U.S. soldiers.

The Sinclair Broadcast Group, which as of last year owned 62 TV stations that reached a quarter of all U.S. households, canceled plans to air the documentary during the razor-close Bush-Kerry race last fall and instead showed only portions of it as part of a broader program.

The Democratic National Committee had complained that "Stolen Honor" amounted to an illegal in-kind contribution to President Bush's campaign, and Kerry's campaign asked for equal time.

Sherwood's suit alleges that Kerry directed the DNC to issue a statement that falsely said the film was produced and funded by "extreme right-wing activists."

The film was funded only by Vietnam veterans from Pennsylvania, according to Sherwood, a Harrisburg resident who served in Vietnam. He and a combat veterans group called the Vietnam Veterans Legacy Foundation filed the federal suit in Philadelphia on Monday.

The suit charges that Anthony Podesta, who ran Kerry's campaign in Pennsylvania, called Sherwood "a disgraced journalist" and "Bush hack" in a widely circulated e-mail.

Kerry's Senate office was preparing a response Wednesday, spokesman David Wade said. Podesta did not immediately return a message.