Sam Smith's 'Stay with Me' is at the centre of a new legal battle.

The award-winning singer has already agreed to pay Tom Petty songwriting royalties over similarities between the track and the 1989 song 'I Won't Back Down' but now songwriter Mark Halper has filed a lawsuit alleging he also deserves credit because a 1986 demo he recorded titled 'Don't Throw Our Love Away' begins with the ''phraseology and significant phrase, 'stay with me'.''

However, according to TMZ, Mark is not suing Sam but a number of record labels and his demands include a request for a recommendation to the National Academy of Recording Arts and Sciences to acknowledge him with a Grammy.

Petty and co-writer Jeff Lynne agreed an out-of-court settlement with Sam last October, in which it was agreed they would both receive a 12.5 percent writing credit.

Petty has previously described the similarities between the two songs as a ''musical accident'' and insisted he bears no ill-will towards the 22-year-old star.

He wrote on his official website: ''About the Sam Smith thing. Let me say I have never had any hard feelings toward Sam. 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.

''Sam's people were very understanding of our predicament and we easily came to an agreement. The word lawsuit was never even said and was never my intention. And no more was to be said about it.

''How it got out to the press is beyond Sam or myself. Sam did the right thing and I have thought no more about this. A musical accident no more no less. In these times we live in this is hardly news.

''I wish Sam all the best for his ongoing career. Peace and love to all.''