In a fall from grace for a man once expected to go far in American politics, Edwards, 57, was charged with six counts, including conspiracy, taking illegal campaign contributions and making false statements, according to the federal indictment.

"Mr. Edwards is alleged to have accepted more than US$900,000 in an effort to conceal from the public facts that he believed would harm his candidacy," Lanny Breuer, assistant attorney general for the Justice Department's criminal division, said in a statement.

Flanked by five lawyers, Edwards pleaded not guilty during a 30-minute hearing in US District Court in Winston-Salem hours after the indictment was filed. The judge set a tentative trial date of July 11.

After the hearing, Edwards told reporters he was innocent.

"There's no question that I've done wrong and I take full responsibility for having done wrong and I will regret for the rest of my life the pain and the harm that I've caused to others," he said with his eldest daughter Cate at his side.

"But I did not break the law and I never, ever thought that I was breaking the law."

Magistrate Judge Patrick Auld released Edwards without requiring him to post bail but ordered him to surrender his passport and stay away from one of the people who made the bulk of the contributions at issue, Rachel "Bunny" Mellon.

Edwards and Mellon met at her home in Virginia last week but a lawyer for her said the meeting was "entirely social and personal. No discussion of (the) case."

If Edwards is convicted, each count carries a sentence of up to five years in prison and a US$250,000 fine.

The indictment accused Edwards of secretly getting the money to help cover up his affair with a campaign worker, Rielle Hunter, knowing that revelations of the liaison and her pregnancy would destroy his 2008 presidential bid.

The affair would undermine "Edwards' presentation of himself as a family man and by forcing his campaign to divert personnel and resources away from other campaign activities to respond to criticism and media scrutiny regarding the affair and pregnancy," the indictment said.