Coldplay's album is out on 6 June in the UK and 7 June in the US

The profits of record company EMI had fallen after the release of X&Y was delayed.

The leak took place on Monday, the day copies were sent to UK radio stations and the day before it went on sale in Japan, its first country of release.

An EMI spokeswoman said tight security had successfully kept the album under wraps until then.

She said: "EMI's anti-piracy efforts have been extremely effective in the pre-release protection of Coldplay's X&Y."

The music industry has battled internet "pirates" in recent years, arguing that fans are less likely to buy the CD if they have already downloaded the album for free.

Coldplay's importance to EMI was highlighted when profits fell 13% after X&Y and an album by Gorillaz were delayed.

Locked-up iPods

Security measures included hosting album playbacks at venues such as Abbey Road Studios for journalists and industry figures instead of sending them copies.

A listening room in EMI's headquarters was equipped with iPods in locked cabinets and CDs that were sent out were labelled with a false name - The Fir Trees - to throw would-be pirates off the scent.

Coldplay themselves have not shown the highest regard for EMI's commercial fortunes.

"Shareholders are the great evil of this modern world," singer Chris Martin said recently.