"Games firms are accusing innocent people of file-sharing as they crack down on pirates, a Which? Computing investigation has claimed. The magazine was contacted by Gill and Ken Murdoch, from Scotland, who had been accused of sharing the game Race07 by makers Atari.

The couple told Which they had never played a computer game in their lives. The case was dropped, but Which estimates that hundreds of others are in a similar situation. The illegal sharing of music, movies and games has become a huge headache for copyright owners.

Some six million people are thought to illegally share files each year, and increasingly firms are getting tough on the pirates.

They are monitoring peer-to-peer sharing networks, such as Gnutella, BitTorrent, and eDonkey, that allow games, music and video to be shared. Atari has appointed law firm Davenport Lyons to prosecute illegal file-sharers.

It has been acting on behalf of several games firms and partner David Gore thinks there are likely to be many more.

The lawyers in the Atari case turned to anti-piracy firm Logistep, which finds those people illegally sharing files via their IP address - the unique numbers which identify a particular computer.

With this number, rights owners can apply for a court order which obliges internet service providers to hand over the account holder's details. "