BT has been banned from claiming in its television advertising that its directory inquiries service is faster at finding numbers than its rivals.

The broadcasting watchdog launched an investigation into the company's claim that "none of our leading competitors is faster at finding numbers" after a rival firm complained about the campaign.

BT based the line on research carried out on its behalf by the pollsters ICM, which it said showed its 118 500 service was quicker and more accurate than its two main rivals.

It claimed the results of the ICM survey had shown it scored a 98% success rate for finding residential numbers compared with The Number with 89%, Dublin-based Conduit with 80% and Yellow Pages at 91%.

But 118 UK, which complained, claimed Conduit was shown as taking far longer to supply a number than it did in reality, and that the survey did not substantiate BT's claim.

The Independent Television Commission upheld the complaint, saying the survey did not provide sufficient substantiation for BT's claim - in fact, it said, the research showed a competitor to be faster at finding numbers.

The deregulation of the directory inquiries market earlier this year sparked a stampede of rival services including The Number, whose comedy 1970s-style runners captured the public imagination.

But many of the new services, including The Number, have come under fire for the quality of their product.

Conduit has already been forced to withdraw the claim that its 118 888 service is "half the price of BT directory enquiries".

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