Britain's ISPs have expressed their discomfort at the mass-adoption of on-demand TV through the BBC's iPlayer service. The corporation initially said it would be introducing users gradually to the Beta service. However, user numbers are known to be over the 120,000 mark.

The Independent reports that Tiscali is among the big names showing concern. BT is also reputedly considering limiting the bandwidth available to the iPlayer, through a process known as "traffic shaping".

The iPlayer works using Peer to Peer (P2P) shared downloading technology. Users don't do a straight download; instead they gather segments of programmes from different users and upload other segments at the same time. The ISPs fear their networks could grind to a halt if, as the BBC suggests , the iPlayer makes up 11 per cent of the catch-up viewing that will take place over the network by 2011.

iPlayer a potential "issue"

"The potential for iPlayer to suck up capacity is a concern and we need a better dialogue with the BBC about that," a Tiscali spokesperson told the Independent. The corporation also thinks 500,000 people will be using it after six months of the open Beta, something which BT thinks "could become an issue" according to the newspaper.

According to the Mail on Sunday, top executives, including BT's Ian Livingston, Carphone Warehouse boss Charles Dunstone and Tiscali UK's Mary Turner have held talks about how to approach the issue. It raises the question of net neutrality and the iPlayer's affect on other services.