US musician Tom Petty said he has no hard feelings towards singer Sam Smith and called the similarities between Smith's Grammy-nominated hit Stay With Me and Petty's 1989 song I Won't Back Down a musical accident.

The Rock and Roll Hall of Famer said in a statement posted to his website that "all my years of songwriting have shown me these things can happen. Most times you catch it before it gets out the studio door but in this case it got by".

He said he never intended to sue Smith and did not know how their settlement agreement became public.

After Petty's song publishers pointed out the similarities, Smith quickly agreed to give Petty and his co-writer, Jeff Lynne, songwriting credits on Stay With Me.

The British artist's breakthrough hit sold more than 3.5 million tracks and is up for song of the year at next month's Grammy Awards.

Petty called the development "hardly news".

"I wish Sam all the best for his ongoing career," Petty said. "Peace and love to all."