The Top 40 as we know it could face a shake-up as chart bosses consider incorporating songs from music streaming sites.

Offering free, legal access to millions of tracks has meant that jukebox services such as WE7 and Spotify have taken off in 2009.

Users can listen to tracks without paying to buy them.

The Official UK Charts Company said it was "bound to" include streaming and subscription services at some point, but not for at least another year.

Because listeners do not pay per track - if at all - those plays would be likely to carry less weight than normal sales.

This would be a big departure from the way the the official singles chart has been compiled since it was launched in 1952.

In effect the charts are a tool to show the hottest tracks of the minute - so ignoring these new technical developments may be impossible.

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