ISPs must stop advertising 'unlimited' broadband deals unless they clearly explain any fair use policies to consumers, says ISP trade association ISPA . The comments follow growing anger from users who have been threatened by their broadband service providers to be cut off after reaching unpublished download limits.

It has told those of its members that keep advertising 'unlimited' services, promising no monthly download limits or loss of bandwidth, to be more transparent and clear about any fair use policies they employ.

Some Pipex broadband users were recently told they would be cut off if they didn't cut back on their broadband use. They complained to Pipex, stating that it had failed to publish details of the fair use policy or specify a gigabyte limit of downloads.

ISPs complaining too

Even among ISPs themselves fair use policies are causing a stir. BT 's Plusnet and Virgin Media have both called for more transparency on fair use clauses.

"ISPA advises its members to be transparent and to explain the consequences of breaking their bandwidth caps or fair usage policies prior to a customer signing an agreement," the trade body said in a statement .

"ISPA recommends members to incorporate any bandwidth caps, allowances or acceptable and fair use policies in their general sales and marketing literature, and on their websites. Information should also be given to the customer at the point of registration for a service."

The Advertising Standards Authority and Ofcom have so far said that advertising 'unlimited' deals is fine as long as the small print says whether a fair use policy applies.