Mercury shortlist to be announced

Radiohead released In Rainbows online on a pay-what-you-want basis

The 12 nominees for this year's Mercury Prize will be announced later.

All albums made by UK and Irish acts are eligible for the award, won last year by the Klaxons with their release Myths of the Near Future.

Big-selling acts who are in contention for the 2008 shortlist include Radiohead, Coldplay and Duffy.

The prize and the accompanying £20,000 cheque have been presented annually since 1992, when they were given to Primal Scream for Screamadelica.

Radiohead gained considerable attention last year by announcing their album, In Rainbows, would be available initially online, with fans paying what they wanted to download the MP3 files.

Coldplay topped the UK and US charts with their latest release, Viva La Vida or Death and All His Friends.

Robert Plant (right) is a contender for his album with Alison Krauss (left)

And Welsh soul star Duffy became the first artist to sell a million copies of an album in 2008, with her debut Rockferry.

If the judges were to favour pop acts on this year's shortlist, Leona Lewis - who spent seven weeks at number one - James Blunt or Adele could be included.

Singer-songwriter Kate Nash may also feature, along with ex-Led Zeppelin star Robert Plant, whose album with country musician Alison Krauss - Raising Sand - was also released in the past 12 months.

The nominations are announced on Tuesday, with the winner confirmed at a ceremony in London on 9 September.