BT has been told it is not allowed to call its internet service fast and reliable in an advert, because it isn't.

The Advertising Standards Authority (ASA) ordered BT to pull banner ads on its website for the BTinternet Anytime offering that claimed its service was fast and reliable, after users complained of busy tones when trying to dial-up connections to the internet.

BT told the watchdog that the problems were being caused by a fault at a number of BT Ignite telephone exchanges in certain areas of the country.

The ASA ruled: "Because intermittent and ongoing problems were preventing some customers from connecting to the internet, the authority considered that the advertisers' claim that their service was reliable, was misleading."

BT promised to fix the problem and provide customers experiencing difficulties with an alternative free dial-up number.

It is the sixth time in the last year that the ASA has upheld complaints against the telco.