A price war has broken out between two UK tabloid papers, the Daily Mirror and the Sun.

Both papers are slashing their weekday price by a third to 20p in order to woo more readers.

The Mirror made the first move, informing staff of the decision on Friday evening.

Within hours, the Sun had followed suit, with a spokesman declaring: "It's war!"

Targeting a younger clientele

Last month, the Mirror was relaunched, dropping its red-top masthead, reclaiming the name Daily Mirror and declaring that it was adopting a more serious news agenda.

It says the price cut is the second phase of that relaunch, aimed at attracting new younger readers and persuading purchasers to take the paper more often.

The Mirror's editor Piers Morgan claimed the move was part of a long-term marketing strategy to rebuild the paper's circulation.

The Mirror has been under pressure recently, after being ordered to pay �3,500 damages to Naomi Campbell for publishing pictures of her leaving a Narcotics Anonymous meeting.

Its sister publication, the Sunday Mirror also ran into trouble last year when an article it published brought about the collapse of the Leeds footballers' trial.

Sales decline

Both the Sun and the Mirror have been steadily losing sales in recent years.

At present, the Sun comfortably outsells the Mirror, with well over three million copies to the Mirror's two million.

The Sun is owned by media magnate Rupert Murdoch, and is part of the News Corporation group that also includes the Times and the News of the World.

The Mirror is part of the Trinity Mirror group that includes the Sunday Mail and the Sunday People.

Share prices in both groups are expected to be under pressure on Monday.

The last major price war in the newspaper world broke out in 1993, and broadsheets such as the Independent and the Daily Telegraph suffered as a result.