Tiscali has expressed concern about the impact of the BBC's iPlayer on the level of demand for bandwidth on its network.
The beta version of the Beeb's on-demand online TV service was launched on 27 July and has already attracted controversy on several fronts.
Tiscali told silicon.com the ISP feels if additional bandwidth is required for customers to be able to use iPlayer, the BBC should pay for it.
A spokeswoman said: "We don't see any reason why some of the cost of transmission over our network shouldn't be paid by the provider of the content. We don't believe that the potential for it to cause congestion is being properly recognised and acknowledged."
According to report in The Independent newspaper, other ISPs have also warned the BBC about the extra bandwidth required for iPlayer. The concern centres on the fact iPlayer works on a peer-to-peer basis, meaning it downloads and uploads content, making it a bandwidth-heavy application.
With the number of users for iPlayer likely to be ramped up over the coming few months, ISPs will almost certainly see a rise in demand for bandwidth.
A spokesman for ISP trade association Ispa said: "iPlayer's impact on broadband networks obviously will have to be assessed and looked at over time."
A BBC statement said the corporation is in regular discussions with the ISPs and is monitoring the costs of providing on-demand video.
It added the delivery of TV programmes over the internet is still a "very young service", which will evolve over the next few years. "We will be playing our part in this, and are working closely with ISPs... to deliver the best experience that we can to the audience," the BBC said.