Britain's media regulator said Thursday it was stepping up its probe into whether BSkyB, the pay-TV giant partly owned by Rupert Murdoch's News Corp., is a "fit and proper" owner of a broadcasting licence.

The Ofcom watchdog has asked News Corp.'s Newspapers division to hand over a cache of documents as part of its investigation into whether the phone hacking scandal at his British newspapers is relevant to BSkyB.

Ofcom wants to see documents relating to the civil cases spawned by the scandal at the News of the World tabloid, which was closed in July after allegations that it hacked the voicemails of a girl later found murdered.

It was later revealed that the paper had hacked the mobile phones of dozens of celebrities and public figures.

"Ofcom is seeking to obtain documents that were ordered to be disclosed in the civil litigation between numerous complainants and News Group Newspapers," an Ofcom spokesman said.

Murdoch's US-based News Corporation has paid out millions of pounds in compensation to hacking victims.

The phone hacking scandal forced News Corp., which owns 39 percent of BSkyB, to drop its bid to take full control of the highly profitable broadcaster in July last year.

The Ofcom investigation into BSkyB, set up five days before News Corp. dropped the bid, had until now focused on publicly-available evidence.

The acceleration in the probe came as Murdoch admitted there had been a "cover-up" over phone hacking, but he told a press ethics inquiry in London on Thursday he had been kept in the dark over the scandal.

The 81-year-old tycoon's youngest son James Murdoch resigned as chairman of BSkyB this month, claiming he did not want to become a "lightning rod" for the scandal.

Evidence given by James Murdoch to a press ethics inquiry this week has left Britain's culture minister Jeremy Hunt fighting for his job after it emerged his department had leaked information to News Corp. as its BSkyB bid was being assessed.