BBC3 and BBC4 planned

BBC Choice and BBC Knowledge are existing digital channels

The BBC has confirmed it is considering a reorganisation of its digital television channels to create BBC Three and BBC Four.

Only digital televisions would be able to receive the new services, which are dependent on the backing of BBC governors and the government.

But with the "switching off" of analogue TV forecast for 2010, the BBC would then be able to offer four main television channels to all viewers in the UK.

The director general of the BBC, Greg Dyke, is expected to outline his vision of the BBC's future in his speech to the Edinburgh Television Festival at the end of the month.

'Fundamental review'

The BBC's media correspondent, Nick Higham, said that with the move towards digital the BBC thinks its channels, including digital channels such as BBC Choice and BBC Knowledge, will have to become more clearly-defined in the kind of programmes they carry and the audiences they appeal to.

He said that under the new plan arts, programmes like the Proms, as well as science and politics, would be on BBC Knowledge.

That would be renamed BBC Four and aimed at the same kind of audience as Radio 4.

BBC Choice, home to programmes like the entertainment news show Liquid News, would be renamed BBC Three and aimed at younger viewers - who have been deserting the BBC.

Greg Dyke will make a key speech on 25 August

A BBC spokeswoman said: "We are planning the two new channels but things are not set in stone.

"We have to go to the governors, who will not meet again until the autumn. It has to be discussed with the secretary of state and then the idea may be put out for public consultation."

At the Banff TV Festival in June, the BBC's director of television, Mark Thompson said public service TV had to change.

"Right now at the BBC, we're engaged in a fundamental review of our TV networks, the most far-reaching and challenging we've ever undertaken," he said.

"The object is to create a suite of channels which live up to the ideals which the BBC was created to promote, but which also make sense in modern digital homes."

BBC radio had solved the problem in the 1960s by giving Radio 1, 2, 3, and 4 different remits and the digital revolution meant television had to do the same, he went on.

"If we can find the funds, and if we can convince the BBC's governors and the wider world that it's the right idea ... we should devote an entire digital channel to serious music and the arts, and to the world of ideas, in science, politics and philosophy."