BT gave leak firm online users' details

BT HAS admitted sending hundreds of customers' personal details to an anti-piracy law firm in an unencrypted document.

The move could put the firm in breach of the Data Protection Act, which requires companies to keep customers' personal data secure at all times.

Its mistake was discovered after a list of more than 4,000 people accused of illegally sharing adult films online appeared on the internet after an attack on the systems of ACS:Law.

BT said its unencrypted document was not the source of the leak. It added that it would "resist efforts to share more customer details with rights holders and those acting on their behalf until we can be sure that alleged copyright infringements have some basis and customers are treated fairly".

Customers' details had been released, BT said, to comply with a court order.

The UK information commissioner, Christopher Graham, has warned he could fine firms that flouted the Data Protection Act up to 500,000.

A BT spokesman said: "BT can confirm it did send unencrypted data to ACS:Law. However, this was not the cause of the leak. At a later date, due to a cyber attack on the systems of the law firm, data that it held was leaked."