MELBOURNE - COLDPLAY singer Chris Martin said on Friday he regrets giving his 'best song' to Australian singer, and former girlfriend, Natalie Imbruglia.

"A bit annoyingly we've given her the best Coldplay song of all time," Martin told The Daily Telegraph newspaper, "but because we're off-cycle we can't do it ourselves.

"Half of me wishes we still had it - but she sounds brilliant on it. I think she has a very unique talent and an incredibly unique voice."

According to a report in The Daily Telegraph, Imbruglia has pushed the release of her new album back to May to include the Coldplay song.

Martin and Imbruglia were an item in 2001 while she was on a 'break' from her now ex-husband Daniel Johns, the lead singer of Silverchair. Martin met his wife Gwenyth Paltrown a year later.

In Australia to promote her new film Closed for Winter, Imbruglia also attended Coldplay's Melbourne show. Her new album, Come to Life will include two songs from Martin.

"If Chris Martin calls with two songs, you don't think, you say, 'Yes'. He's a great songwriter," she said.

Martin and imbruglia recorded the songs in a London studio in January with Paltrow and children Apple and Moses present.