Robbie Williams is one of EMI's best selling artists

A merger between the two has long been on the cards, in an attempt to compete more effectively with larger rivals Universal Music and Sony BMG.

Warner Music said it had carefully examined the offer, but decided it did not benefit shareholders.

The rejection came just 24 hours after EMI had tendered its $28.50 a share offer to Warner.

"This is disappointing, as we believe the logic for combining the two businesses is compelling," said Lorna Tilbian, an analyst with Numis.

If the two had merged, the combined company would have held about 25% of the recorded music market, based on figures from the International Federation of the Phonographic Industry.

Warner Music has the rights to more than a million songs via its publishing arm Warner/Chappell Music.

Artists recording on the Warner label include Madonna and James Blunt, while EMI's list includes Coldplay, Robbie Williams and Norah Jones.

In 2000, attempts to merge EMI and Warner Music were blocked by European competition regulators.