A quarter of teenagers in the US say they are prepared to shell out $500 for an iPhone when it launches in June.

The Piper Jaffray survey also found that 84 per cent of American teens were aware of the Apple iPhone.

13th bi-annual teen market survey was conducted by analysts at Piper Jaffray among 500 teenagers at 11 high schools across the US. The researchers found that 82 per cent of the teens surveyed owned an iPod, up from 79 per cent last autumn.

The survey also found that 64 per cent of teens are getting their music free from peer-to-peer file sharing services while 36 per cent purchase music from online stores like iTunes. The good news for the music industry is that Piper Jaffray's autumn survey last year found that 28 per cent were purchasing tracks from online music stores. Two years ago that figure was just 20 per cent.

Piper Jaffray senior research analyst Gene Munster commented: "We believe that the teen demographic is a critical component of long-term growth in both markets, and Apple is clearly leading the category."