Labour's Lord Mandelson's proposal is that people who illegally download films and music should have their Internet connection cut.

The view, something of a u-turn for the government, was formed after Mandelson dined with the multimillionaire Hollywood mogul David Geffen during his holiday in Corfu. The idea had originally been rejected in the government's Digital Britain report earlier this year.

Writing in newspaper, Charles Dunstone of TalkTalk, Ian Livingston of BT, Tom Alexander of Orange UK, Deborah Prince of Which?, Jim Killock of Open Rights Group and Ed Mayo of Consumer Focus said such plans threaten broadband consumers' rights and the development of new attractive services.

"First, any decision to move to harsh and punitive measures such as disconnection must be genuinely underpinned by rigorous and objective assessment by Ofcom," the group write in The Times.

"Second, consumers must be presumed to be innocent unless proven guilty. We must avoid an extra-judicial 'kangaroo court' process where evidence is not properly tested and accused broadband users are denied the right to defend themselves against false accusations. Without these protections innocent customers will suffer."