The trial is being done at the behest of the British Phonographic Industry and will let the BPI perform the scans and trace them to individual Internet connections. Virgin is expected only to take part in the deal by relaying account information and halting service when necessary.

Virgin's move comes after pressure by the BPI and the UK government to institute a voluntary anti-piracy system. British officials have previously warned that they may impose anti-piracy filtering laws in response to what they have alleged is the destruction of the UK music industry by unchecked copying.

Arguments by the government are believed to come after prompts by the BPI, its international equivalent, and other music and movie groups that insist constant monitoring is necessary to protect copyrights. Critics have responded by labeling the scans an invasion of privacy and unlikely to succeed against determined pirates, who can modify or encrypt files to avoid superficial scans.