Democrat John Edwards looks down at his notes as he announces his withdrawal from the presidential race in the Ninth Ward of New Orleans, La., on Jan. 30, 2008. (Alex Brandon/Associated Press)

Former U.S. Democratic presidential candidate John Edwards, disgraced since his disclosure of an affair while his wife was undergoing cancer treatment, has acknowledged that federal investigators are assessing how he spent his campaign funds.

Edwards, who admitted last year he had an affair with a woman whose firm received more than $100,000 from his political action committee, said in a statement on Sunday that he is "confident that no funds from my campaign were used improperly."

"However, I know that it is the role of government to ensure that this is true," the former North Carolina senator's statement said.

"We have made available to the United States both the people and the information necessary to help them get the issue resolved efficiently and in a timely matter."

U.S. media reported over the weekend that U.S. attorney George Holding is probing whether any of Edwards's campaign or fundraising organizations paid money to Rielle Hunter to keep the affair quiet.

Edwards, who was the Democratic vice-presidential nominee in 2004, confessed to ABC News in August 2008 that he had lied repeatedly about the affair with 42-year-old Hunter.

In 2006, Edwards's political action committee paid $100,000 in a four-month span to a newly formed firm run by Hunter, who directed the production of four web videos showing Edwards in supposedly candid moments, as well as in a public speech talking about morality.

Since announcing the affair, Edwards has remained largely secluded, and he cancelled all his public appearances before the November election because he said he didn't want to be a distraction for then Democratic presidential candidate Barack Obama.

His wife, Elizabeth, who is terminally ill with cancer, will soon be releasing a book talking about the affair. In the book, she reportedly writes that news of the affair made her vomit and also describes Hunter as "pathetic."

With files from The Associated Press