A British music body has attacked internet service providers for their "indifference" to illegal music downloads by their customers and may consider taking legal action.

The Music Business Forum, an umbrella group that represents performers and record labels, wrote to ISPs including BT, Tiscali and NTL saying they have a "corporate responsibility" to discourage illegal downloading. The companies are "indifferent as to whether consumers' access to music is legitimate or illegitimate," the letter, seen by Times Online, said.

Scott Walker, a policy manager at British Music Rights, a member of the group, said service providers were taking advantage of the prospect of free music to attract customers. He said that while ISPs were not specifically promoting illegal downloading in their advertising campaigns, they were not discouraging it.

John Kennedy, chairman of the International Federation of the Phonographic Industry, another member of the group, said: "Internet Service Providers have to take their share of responsibility for keeping the traffic on their networks legitimate. ISPs are doing very well out of digital music - it is helping drive their revenues and it is being liberally used in their marketing strategies."

Despite the music industry’s frustration at what it called "vast networks of illegal downloading", Mr Walker insisted the purpose of the letter was "to encourage ISPs to collaborate with the music industry to help curb illegal downloading". It was not a "veiled legal threat".

But Emma Pike, co-chairman of the MBF, said the organisation "would not rule out exploring the legal route" if ISPs do not act on its requests.

Lawyers said such an action would be extremely difficult, which could explain the group's "softly-softly" approach to an issue that is costing its members hundreds of millions of pounds in lost revenues each year.

Tom Frederickse, a former music producer who specialises in digital media law at Clintons, said there is no clear claimant as the MBF cannot launch a general legal action on behalf of its members or the wider industry.

Furthermore, ISPs can hide behind the so-called "mere conduit" defence, whereby they claim they are merely providing a service to access the internet and that they are not liable for how individuals use that service. The defence has been repeatedly held up in courts across Europe.

"European e-commerce regulations give ISPs an extremely strong shield to hide behind," Mr Frederickse said. "It’s very hard to successfully sue an ISP."

Despite acknowledging the difficulty in challenging ISPs with legal action lawyers said the music industry may have no other choice. One lawyer said: "Internet companies are making so much money as a consequence of illegal downloading and music companies are losing so much, that the issue seems destined to head for the courts."

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