Britain's media regulator Ofcom has launched an investigation into Sky News, which has admitted to twice hacking into emails to generate a story.

Sky News said earlier this month that it had hacked into emails in 2008.

It insisted it had acted in the public interest because it had shared the information with the police and helped to secure a criminal conviction.

The admission was seen as damaging to the successful channel. Its parent company BSkyB is 39% owned by Murdoch's News Corp.

It has been mired in a phone hacking scandal at its British newspaper arm.

As a result, BSkyB is being investigated as to whether its owners and directors are fit to own a broadcast licence.

"Ofcom is investigating the fairness and privacy issues raised by Sky News' statement that it had accessed without prior authorisation private email accounts during the course of its news investigations," a spokesman said.

"We will make the outcome known in due course."