A representative for Tim McGraw has dismissed a tabloid report suggesting the country star has maintained a secret relationship with the son of an ex-fiancee behind his wife Faith Hill's back.

Editors at America's National Enquirer magazine claim McGraw helped to raise Tyler Zarbo while he was engaged to the child's mum, Kristine Donahue, in the early 1990s.

The engagement was broken off and McGraw went on to wed Hill in 1996, but the article suggests the country hunk continued to stay in touch with Zarbo without his new wife's knowledge.

Zarbo, now 23, told the publication, "Tim McGraw was like a father to me when I was growing up. He saw me as the son he never had, and we've stayed in contact. I wish he could have remained as my substitute dad, but it just wasn't meant to be."

However, McGraw's spokeswoman, Mary Hilliard Harrington, insists the claims have been fabricated.

She tells People.com, "The National Enquirer story is full of inaccuracies and misrepresentations about Tim and Faith. We aren't going to comment on false statements that appear to have been sensationalised for the purpose of selling tabloid magazines."

McGraw and Hill are parents to three daughters, aged between 11 and 15.