BBC4 is emerging as one of the prospective casualties of the corporation's plans to find 20% of cost savings, with the scope of the channel expected to be scaled back.

More repeats are also expected across the BBC's channels as a result of the corporation's Delivering Quality First cost-saving initiative.

Other options still being discussed include axing some of BBC2's daytime schedule and cutting back on dramas on BBC3 and BBC4 – leaving the bulk of drama to BBC1 and BBC2.

Digital channels BBC3 and BBC4 have been put under the microscope and it is understood BBC3 is seen as more distinctive. BBC3 is likely to remain largely intact but may be asked to concentrate on its key areas of factual and comedy.

The youth-focused general entertainment channel only airs a few dramas, such as supernatural series Being Human, but could be asked to scale back on the genre.

Management fears an outcry if BBC3 is tampered with and it has proved a useful tool for attracting young audiences to the BBC.

It has also been a "nursery slope" for hit BBC comedies, such as Gavin & Stacey and Little Britain and has shown acclaimed documentaries such as Our War.

However, more radical changes are being considered for BBC4 to turn it into a so-called "arts and archive" channel.

Despite Bafta award-winning single dramas such as The Road to Coronation Street and biopic Enid, some corporation executives have questioned whether BBC2 should instead be airing such shows.

BBC4 has also commissioned a smaller number of comedies, such as The Thick of It and Getting On, which have attracted critical acclaim.

In the BBC's statement of programme policy, published earlier this year, BBC4 controller Richard Klein described his channel's aim "to be British television's most intellectually and culturally enriching channel, offering an ambitious range of UK and international arts, music and culture", but with no mention in his opening summary of drama or comedy.

In his vision for the service for the next 12 months, Klein described BBC4 as "the gold card channel for arts and culture, approaching subject matter at a level of depth, detail and authority second to none". In a statement spanning nearly 650 words, comedy and drama – which are the most expensive television genres to produce – were relegated to just one line. "The aim is to offer discourse and insight through factual, drama and entertainment programming," he said.

One source said: "The scope of BBC4 is under threat. The relationship between the four major channels is being looked at."

The BBC director general, Mark Thompson, recently updated staff on the progress of DQF, which is being carried out as a result of last year's flat licence fee settlement.

Thompson ruled out the merger of local radio with BBC Radio 5 Live or dropping the BBC Parliament channel from Freeview.

He did not rule out axing a service entirely. "We haven't ruled out service closures yet but the work so far suggests there's a smarter way of making savings without taking entire services away from the public … because every single service is strongly valued by its audience," Thompson said.

BBC management recently met with the BBC Trust to discuss progress on DQF before final decisions are made next month.

The trust has now appointed Ernst & Young as advisers to scrutinise the financial impact of management's plans.

A BBC Trust spokesman said: "We are not going to comment on speculation ahead of the trust reaching final conclusions on Delivering Quality First."

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