Media regulator Ofcom will conduct new research into the popularity of hi-def TV before it decides a final plan for the Digital Dividend.

Ofcom chief executive Ed Richards said that his agency will "look at the public interest case" for reserving some analogue spectrum for hi-def Freeview channels after the switch to digital TV.

Ofcom has already conducted research into the popularity of HD compared to other potential uses of the former analogue TV spectrum, which didn't reveal a general preference for hi-def. But the research has been questioned because most of the respondents had never seen high definition, mobile TV or other uses they were asked about.

According to The Guardian, Mr Richards added: "We are going to do more research and we are going to try and make it more sophisticated. We've got to be careful and cautious about that kind of work but we are doing more work on it.

"Securing the high quality that there is currently across the range of the market must remain at the heart of our purpose and vision."

He told the Voice of the Listener and Viewer conference that Ofcom has received more than 750 applications for the analogue spectrum, ranging from mobile phone companies to traditional broadcasters.

Under Ofcom's current Digital Dividend Review proposal, all of the former analogue spectrum will be auctioned off to the highest bidders.

Mr Richards also stressed that Ofcom isn't charged with raising money for the Treasury, which hopes to raise £36billion over the next four years by selling off assets such as radio and broadcasting spectrum.

"We have no obligation, duty or responsibility to maximise revenues for the Treasury," he said. "We have no pressure on us."