Telephone sex line operators have blamed BT for a dramatic fall in their business. They say that new restrictions on who can access their lines, and administrative delays by BT, are to blame.

Since the end of July, 0898 services have been limited to registered users who have obtained a personal identification number (Pin) from BT. The system was introduced after concern over children ringing adult phonelines, and research conducted by BT which indicated that 90 per cent of customers supported an opt-in scheme.

Some industry observers also believe it signals BT's intention to distance itself from adult telephone services. Since the introduction of the register many companies providing 'one-to-one services have closed or laid off staff.

Sue Horwood, who runs Chatterbox Ltd in Camberwell, blames the contraction on a failure by BT to issue Pins quickly. Prior to the opt-in system Chatterbox employed 75 female operators dealing with up to 2,000 calls a day - mostly of a sexual nature. Now only five women are employed while the number of calls daily can be as few as 30. 'This is crippling my business. I used to turn over pounds 25,000-pounds 50,000 each month, but it's slumped to just a grand, said Ms Horwood.

'BT want us to roll over and die because they don't want to be saddled with the adult side of the business any more. They haven't advertised the opt-in service enough.

BT said an administrative error

had led to delays in issuing Pins, but that was now on schedule. It added that the opt-in arrangement had

been advertised nationally and that customers had received information with their bills notifying them of

the change.