Apple fired its first major salvo against competing music download services last night, revealing iTunes Music Store to have outsold Roxio's new Napster service by five-to-one.

Apple claims it sold 1.5 million songs through its store "in the same period" that new arrival Napster sold 300,000 tracks. The period was between October 28 and November 3.

More than 17 million songs have been purchased and downloaded from the iTunes Music Store since it launched in April 2003, Apple said. According to Nielsen SoundScan, the iTunes Music Store took over 80 per cent of the market share for legally purchased downloads last week.

An exultant Apple CEO Steve Jobs, who on Wednesday referred to the iTunes Music Store as the "Microsoft of music stores", said: "During Napster’s first week of operation, the iTunes Music Store sold five times as many songs as Napster did – 1.5 million versus 300,000.

"The unbeatable combination of iPod and iTunes offers music lovers a seamless experience for buying, managing and listening to their digital music collections anywhere," he said.