Britain's media watchdog launched an investigation on Monday into two cases of email hacking by Sky News, the satellite broadcaster partly owned by Rupert Murdoch.

The news channel admitted earlier this month that it illegally hacked into the emails of a canoeist who notoriously faked his own death in a life insurance scam, as well as the account of a suspected paedophile.

A spokesman for the Ofcom watchdog told AFP it was investigating whether Sky News had broken privacy regulations in both cases.

"We aim to get the investigation done within 90 days," he said. "Sky News will be given the opportunity to make representations."

A Sky News spokeswoman told AFP: "We stand by these actions as editorially justified."

Sky admitted on April 5 that it had authorised a reporter to access emails belonging to John Darwin and his wife Anne. The couple faked his death in a 2002 canoe accident before starting a new life in Panama with the insurance payout.

But the broadcaster insisted the hacking was in the public interest as material provided by the channel was "pivotal" in the successful prosecution of the British couple in 2008.

The same reporter, Gerard Tubb, was authorised to access the emails of a suspected paedophile and his wife, but this did not result in any material being published or broadcast.

The revelations came after a huge phone hacking scandal engulfed Murdoch's British newspaper arm News International, forcing the Australian-born tycoon to shut down the 168-year-old News of the World tabloid last July.

At a government inquiry into press standards set up in the wake of the phone hacking scandal, Sky News chief John Ryley said on Monday that journalists "need at times to shed light into wrongdoing".

"Journalism is at times a tough business," he told the Leveson Inquiry, adding that on "very, very rare" occasions, Sky News might consider breaking the law in pursuit of a story.

Murdoch is due to appear at the inquiry on Wednesday and Thursday.

Sky News is owned by pay-TV giant BSkyB, of which 39 percent belongs to Murdoch's US-based media empire News Corp.

Ofcom is also investigating whether BSkyB is a "fit and proper" holder of a broadcasting licence in the wake of the phone hacking scandal.

A spokesman for the watchdog said the two investigations into the broadcaster were unrelated.

James Murdoch, Rupert Murdoch's youngest son who is under continued pressure over phone hacking, resigned as BSkyB chairman on April 3 saying he did not want his association with the scandal to damage the broadcaster's reputation.

The 39-year-old has always denied knowing that the illegal practice was widespread at the News of the World, but he resigned as executive chairman of News International in February.

James Murdoch is due to testify before the Leveson inquiry on Tuesday.

John Darwin was jailed in 2008 for six years for his scam and his wife, who claimed just over 500,000 pounds ($805,000, 612,000 euros) in life insurance payouts, was jailed for six and a half years. The couple were both freed last year.