News that Napster may be forced to shut down sparked a rush of last-minute downloads from the MP3-sharing service, a study shows.

According to data from Internet-oriented market researcher NetValue, there was a four-fold increase in the volume of Napster downloads between 26-28 July. Friday, 28 July was Napster's deadline for closure before the US Appeal Court overruled an earlier District Court judgement against the software company.

MP3 watchers says the revelation is likely to please the Recording Industry Association of America (RIAA) – as it adds weight to its contention that Napster is used to avoid paying for music.

In the run-up to the trial last month, more than eight million people used Napster – more than 40 per cent on the previous month, according to NetValue.

UK usage has seen a six-fold increase on normal levels between March and June, the research shows.