London-based anti-piracy law firm ACS: Law could be forced to pay £500,000 in fine for reveling identities of thousands of people online.

The issue emerged after ACS: Law revealed the names and other personal details of around four thousand Sky customers, who allegedly were sharing adult films illegally.

In case the Information Commissioner’s Office (ICO) finds that the firm failed to protect the personal details of the customers it could levy a massive fine on the firm.

The ICO said that they would contact ACS: Law to get to the bottom of the issue and to determine what action to take.

Commenting on the topic, the ICO said, “Any organisation processing personal data must ensure that it is kept safe and secure. This is an important principle of the act.”

The law firm claimed that it revealed the list after users of the message board 4chan attacked firm’s website in retaliation for its anti-piracy efforts.

Meanwhile, Sky suspended all cooperation with ACS: Law. A spokesperson for the broadcaster said the suspension would remain in effect until the anti-piracy law firm promises the satisfactory security of the personal information of its customers.