Coldplay haven't finished any songs for their new record.

The band originally planned to release the follow up to their fourth album 'Vida La Vida Or Death And All His Friends' in 2010, but finishing their new album - which they have been working on for two years - is taking longer than they originally thought.

Lead singer Chris Martin surprised fans last week when he unveiled a new song, 'Wedding Bells' at a conference in California, but a source close to the band said not even the full arrangement of that song is complete.

The source told fan site "Chris said that although they are close to finishing lots of songs, they have not actually finished anything at all yet, even 'Wedding Bells'!

"They band always seem to finish a huge bulk of songs together. He was very confident anyway, but said that the last two months have not been as completely productive as first imagined.

"But he also said 'You can't rush things like this!'"

Coldplay originally retired to the studio in 2009 to start recording, and at the time Chris - who is joined in the band by guitarist Johnny Buckland, bassist Guy Berryman and drummer Will Champion - was "banned" by producer Brian Eno, so the other members of the group could write ideas without him.

He explained: "Brian said that he still wanted to work with us on the next album but that I was banned from the studio! He said that it would be better without me for the first two weeks - 'You can do better without the singer!' he said.

"It has turned out to be a good idea though because the band's been free to try out loads of weird things without me getting in the way."

It has also previously been reported the 'Violet Hill' group will pursue a more stripped back, intimate sound for the new album.