A groundbreaking deal between the music industry and broadband companies to tackle illegal downloading that will see thousands of warning letters sent to UK internet users will be unveiled by ministers today.

The UK government will reiterate its threat to legislate next year should the voluntary measures prove ineffective in curbing the rampant online piracy that has crippled the music industry's revenue on CD sales. An estimated 19 out of 20 internet downloads are carried out for free on illegal sites, costing billions of pounds in lost revenue.