
"The internet was not set up with a view to distributing video. We have been improving our capacity, but the bandwidth we have is not infinite," Mary Turner, chief executive of Tiscali UK, told the Financial Times.
"If the iPlayer really takes off, consumers accessing the internet will get a very slow service and will call their ISPs to complain."
The move could be the first in a war to abolish the principle of net neutrality in the UK. This would allow ISPs to price different internet content according to use, and allow companies to buy faster data transmission.
"We are in regular discussions with ISPs and are monitoring the costs associated with video-on-demand," said the BBC in a statement.
"The delivery of TV programmes over the internet is still a very young service, and we can expect everything from service propositions to ISP service packages and consumer electronic equipment in the home to evolve over the next few years.
"We will be playing our part in this, and are working closely with ISPs and consumer electronics manufacturers to deliver the best experience that we can to the audience."