Six of the UK's biggest internet service providers have signed up to a "ground breaking" plan with the music industry to tackle piracy.

The deal, negotiated by the Department for Business, Enterprise & Regulatory Reform branch of the government, will see hundreds of thousands of letters sent to net users suspected of illegally sharing music.

The plan is to make a "significant reduction" in illegal music sharing with BT, Virgin, Orange, Tiscali, BSkyB and Carphone Warehouse all signed up.

An enforcement team set up by the BPI will monitor websites where music is available to copy, such as LimeWire and BitTorrent, and note the IP addresses of those who use these sites.

This info will be passed onto the ISPs, who in turn will send warning letters to the relevant address - with parents responsible for what their children may be downloading without their knowledge.

Organisations involved include Ofcom, British Music Rights and The British Phonographic Industry who want the ISPs to cut off the service of repeat offenders, something that not all the companies have agreed to.

What has been agreed, however, is "traffic management", meaning that downloaders could see a sudden curtailment of their internet speeds to make downloading more difficult, and "traffic filtering", monitoring of the files downloaded to an account to check whether they have paid for them.

The agreement also means the net firms have to ensure their customers know it's illegal to share copyrighted music, and apparently also commits the firms to develop legal music services, something Sky took a step towards this week with their announcement of an unlimited music service with Universal Music.