A NEW TV age dawned yesterday as the BBC announced it is to start transmitting its first four digital channels next Wednesday.

BBC1, BBC2 and BBC News24, will all be transmitted in widescreen on both satellite and terrestrial systems and will be joined by a new channel, BBC Choice.

Plans for investment in core services, including programme-making and digital technology, were revealed simultaneously at the launch of BBC Scotland's Annual Review in Glasgow and at a news conference in London.

In the biggest BBC channel launch since BBC2, BBC Choice is described as a companion to the two main channels and will include extended sport, theme nights built around highlights like costume drama, and many new programmes, all in widescreen.

In time, other services will include BBC Learning, which will have interactive elements, and BBC Parliament, with coverage direct from the House of Commons, House of Lords and the new assemblies in Scotland, Wales and Northern Ireland.

BBC Scotland will have an opt-out slot on BBC Choice between 10pm and midnight, which it aims to fill with a variety of new sport, news and entertainment packages together with a small number of repeats of popular shows from its archives.

Controller John McCormick said news and current affairs output would be beefed up and new digital transmission suites and other hi-tech improvements installed in anticipation of the twin birth of digital broadcasting and the Scottish Parliament.

He said the corporation was de-termined to remain at the heart of Scotland's broadcasting industry: ''We know we will only deserve to do so if we continue to provide a range of programmes that match the mood of the nation as we move beyond the millennium.''

Not all the extra cash will go on politics and digital TV: an additional #1.5m will be ploughed into producing new entertainment programmes. The decision follows a public consultation exercise which saw Scottish viewers demand more home-grown hu-mour.

Although viewers will not have to pay for the new digital channels, new hardware is needed to receive the signals.

Mr McCormick admitted he expected audience figures for the digital service to be ''very low'' to begin with until the service beds in and set-top decoders become more widely available.

From October 1, set-top boxes to receive digital satellite, including BSkyB's 200-channel offering, will be in the shops. Terrestrial set-top boxes, capable of receiving about 30 channels, will be available before Christmas, and Sony announced its fully integrated television sets, with the digital technology built in, will be on display in November.

However, consumer groups voiced fears that many new services would not be available to poorer people unable to upgrade their sets, but the BBC promised it would never hive off its best programmes to pay-TV.

Ruth Evans of the National Consumer Council, said: ''The potential benefits of digital television are beyond anybody's question. But what about people who are going to be excluded?'' She said set-top boxes for either terrestrial or satellite services were likely to cost #200, even if the viewer does not subscribe to pay-TV services, and then there was the cost of buying a widescreen television.

BBC director-general Sir John Birt said the corporation aimed to make its free services available to all, not just those who could afford to pay subscriptions. But he added: ''We are going to see the emergence of pay television. The cost of being an active consumer of audio visual services is going to rise immensely.''