Apple iPod owners are less concerned about the size of their music player than they are about the lack of a built-in radio in the iconic device, new research shows.

US research firm Jacobs Media polled some 25,000 people via radio station websites asking what features they would like to see added to their digital music player.

Of those who already owned some kind of digital music player, a third (33 per cent) said they wanted their next device to have a built-in FM tuner. That number rose to 43 per cent among those who owned an iPod .

Some 53 per cent of respondents did not already own an Apple iPod or other digital music player. Of those, 45 per cent said that it was "highly likely" they would buy one this year.

Only one in four (24 per cent) wanted more storage capacity in their MP3 players, and only 3 per cent said they wanted their next player to be physically smaller in size. A bigger screen (7 per cent) and video playback (7 per cent) were other wishes.

Last week, analyst company iSuppli predicted that sales of digital music players would continue to rise until at least 2011.