Former President Bill Clinton (search) defended John Kerry on Sunday, telling FOX News that one of the independent campaign ads questioning Kerry's Vietnam service bore "false witness."

"There has been too much controversy or discussion about the politics of it and little about its merits," Clinton told FOX News' Geraldo Rivera. "The ad was paid for by a big supporter of the president and the campaign's lawyer and one of the military advisers participate accurately in it and it was wrong. It was false witness."

So far, the group Swift Boat Veterans for Truth (search) has released several ads critical of Kerry's actions or comments during and after the Vietnam War. Although he did not specify which ad he was talking about, Clinton likely was talking about an ad the group ran that said Kerry was lying about what happened in Vietnam.

"All the guys that were on the boat with him say he told the truth. The records say he told the truth. There have been no serious disputes about any of the incidents in which he earned his medals," Clinton said outside the Landmark Riverside Church in upper Manhattan.

Kerry commanded a swift boat during his four months in Vietnam during 1968 and 1969 and during that time, got three Purple Hearts for injuries sustained, a Bronze Star for saving the life of Special Forces Lt. Jim Rassmann (search), and a Silver Star.

The Swift Boat Veterans, many who served on other boats, have challenged many of Kerry's stories about what happened in Vietnam. But the men who served with Kerry on his boat have backed Kerry's version of events.

"There is no hornet's nest, this is completely made up by people who were not on that boat … all the records from the Navy show that what John Kerry said happened, happened," Elaine Kamarck, a former adviser to Al Gore in 2000, told FOX News on Sunday.

The Kerry camp argues that Swift Boat Veterans for Truth has the support of the Bush-Cheney re-election campaign and has said the Bush camp is participating in a "smear" campaign against the Massachusetts senator. The Bush team denies that and has denounced all unregulated independent groups — known as 527s — but has not specifically asked the Swift Boat Vets group to pull its ads.

"Trying to link President Bush to those ads ... is completely untrue," Nick Calio, a former assistant to Bush, told FOX News on Sunday. "I think it's grotesquely disingenuous for President Clinton … [to criticize] people whining about or disagreeing with Senator Kerry while the president sat back for months while the Democrats went on the offensive with attack ads against him." 

Clinton and his wife, Sen. Hillary Rodham Clinton, D-N.Y., attended services at Landmark Riverside Church. The topic of the sermon: to reconnect America to its moral, spiritual and democratic values.

When Clinton was in the White House, he weathered an effort to be ousted from office because he lied about a relationship he had with an intern, Monica Lewisky. Plus, Republicans frequently questioned the ethics of Clinton and other members of his administration.

"You have been a victim of slings and arrows, they don't necessarily have to be true to be effective," Rivera noted to Clinton.

Clinton responded: "That's why I think we need to answer back. But I think, I think in the beginning John couldn't believe it ... If you've never been through this kind of thing before — where people question your integrity and your very core — it's disorienting, but I think he's got a good answer.

"The facts are on his side and he'll prevail," Clinton said.

For a transcript of Clinton's comments, click here.