A secret DNA test proves former presidential candidate John Edwards is the father of his former campaign aide's baby, the National Enquirer reported Wednesday.

The Enquirer, which last year broke the story of Edwards' affair with campaign videographer Rielle Hunter, said the test was taken after Hunter tried to get financial help from Edwards for her 18-month-old daughter, Frances.

Hunter apparently agreed to testify to a federal grand jury investigating whether Edwards broke campaign finance law by paying "hush" money to Hunter and another aide who claimed paternity of the child. Hunter was spotted last week in Raleigh, N.C., entering a federal courthouse, where she spent nine hours.

Edwards adamantly denied during a confessional interview with ABC News last summer that he had fathered a child with Hunter, and he said he welcomed a paternity test. His wife, Elizabeth, has said while promoting her book that she doesn't know if her husband is the father.

Former Edwards aide Andrew Young, who made a similar courthouse visit while the grand jury was sitting last month, said in 2007 he was the child's father. Hunter said around the same time that Young was the father and the birth certificate does not list a father's name.

Edwards has admitted to an affair with Hunter that he says ended in 2006. That year, Edwards' political action committee paid Hunter's video production firm $100,000 for work. Then the committee paid another $14,086 on April 1, 2007.

Edwards, a North Carolina senator from 1998 until his vice presidential bid in 2004, acknowledged in May that federal investigators are looking into how he used campaign funds. Grand jury proceedings are secret, and the U.S. attorney's office in Raleigh has declined to confirm or deny an investigation.

Young hasn't spoken publicly since saying he was the father in 2007. 

Click here to read The National Enquirer article.

The Associated Press contributed to this report.