Persistent illegal downloaders will be disconnected from the internet under new government legislation.
The cut-off will be implemented as a “last resort” if web users fail to respond to two warning letters.
The measures, which are expected to come into effect in April next year, were announced by business secretary Lord Mandelson.
"It must become clear that the days of consequence-free widespread online infringement are over," Mandelson said at a digital creative industries conference.
"Technical measures will be a last resort and I have no expectation of mass suspensions resulting."
The government plans to monitor the effectiveness of the warning letters over an initial 12-month period.
If illegal file-sharing fails to drop by 70% by April 2011, then internet disconnection will be introduced in August 2011.
The British Phonographic Industry (BPI) has welcomed the proposals, but some ISPs have aired caution.