Bruno Mars would write a song with Robert Pattinson.

The 'Just the Way You Are' hitmaker has recorded a track, 'It Will Rain', for movie 'The Twilight Saga: Breaking Dawn - Part 1" and would be open to working with its star, who has musical aspirations of his own.

Bruno told Billboard.com: "Why not? I'm down for anyone that wants to work and thinks I can contribute."

Robert has so far recorded two tracks for the original 'Twilight' soundtrack and was recently rumoured to be planning a debut album.

Meanwhile, Bruno promises 'It Will Rain' captures the darker side of the love between Robert's Vampire character Edward Cullen and his mortal girlfriend, Bella Swan, played by Kristen Stewart.

He said: "The 'Twilight' movies for me are a love story. But it's a dark love story.

"And I think the best way to describe the song is: it's the darker side of love. I think that pretty much sums it up."

Bruno added he didn't record the song until after he had seen a preview of most of the film.

He said: "'It Will Rain' started off with me and the guitar and I just had this melody in my head and basically laid it down after I saw the film."

'It Will Rain' is released globally on September 27 except for in the UK, where it will go on sale in Early November.