One of the directors of Ofcom has fired a warning shot across the bows of the BBC hinting that it may be able to intervene if it unfairly promotes its digital services or spin-off magazines such as Top Gear and Top of the Pops.

Dave Edmonds, currently the director general of telecoms watchdog Oftel who is to serve on Ofcom's board of directors, said he would be asking searching questions about the BBC's activities in his new role.

Ofcom will share powers over competition regulation with the office of fair trading.

The BBC's fair trading practises have previously been monitored by the OFT.

"I'm not for a moment accusing the BBC of abusing a dominant market position," Mr Edmonds said.

"But Ofcom will be able to ask some interesting questions in a way that regulators have not been able to ask before."

Mr Edmonds gave the BBC's cross-promotion of its digital services on its main TV and radio channels as an example of the sort of activity he might ask the corporation to justify in his new Ofcom role.

"These are the sort of questions I'll be asking as an Ofcom board member. But I'll be asking them from a background of knowing how dominant players operate," he said.

At Oftel, Mr Edmonds gained plenty of experience of regulating a dominant player in the telecoms market from his dealings with BT.

The BBC has come under fire from critics concerned about the way it cross-promotes digital services, books and magazines on its main networks.

Many rival media companies also claim the BBC's expansion into digital TV and the internet is anti-competitive.