The director general of the BBC is to face "extremely difficult questions" at Holyrood this week after reportedly halting the idea of a 'Scottish Six' evening news bulletin for the network.

Sir Tony Hall has, according to a report, rejected the Scottish Six - a new evening programme to replace Reporting Scotland and the Six O'Clock News - a plan which has been developed in various pilots at BBC Scotland in recent months.

It is believed Hall will formally announce the decision when he appears before MSPs of the Culture Committee at Holyrood on Thursday, although yesterday BBC sources said news of a Scottish Six rejection was "speculation."

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BBC Scotland pilots, with various potential formats, have been trialled at Pacific Quay in Glasgow for months, fronted by presenter Jackie Bird, and was a key project for both the new director of BBC Scotland, Donalda MacKinnon, and its head of news, Gary Smith.

Ms MacKinnon has previously said that there were "deficits" in BBC Scotland's news output and indicated a desire to shake up its news broadcasting.

Sources last night suggested that the BBC could go with a compromise plan, with a new BBC Scotland bulletin beginning at 6.20pm, a forty minute show boosted with extra funding resources.

John Nicolson MP, the SNP culture spokesperson, and a former BBC journalist, said: "If the BBC decide not to go ahead with the Scottish Six it will represent an extraordinary lack of ambition and commitment to Scotland.

"As our national debate continues over Brexit and independence - a properly funded Scottish Six has never been more necessary.

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"I have no doubt it would draw on the very best of our journalistic talent to produce programmes of the highest standard.

"Indeed, the BBC’s Good Morning Scotland is a perfect example of how a Scottish-based programme can deliver a mix of Scottish, UK and international news with a running order decided on news merit. It is absurd to suggest that the same format cannot be delivered on television."

He added: "I will be very disappointed for the staff at BBC Scotland if the long planned launch does not go ahead.

"I know how keen they were to take on the exciting challenge of a Scottish Six.

"They have been working incredibly hard on pilot programmes and appear to have been led up the hill and back down again by their management."

The Scottish Six has been a topic of debate for 20 years, and a previous plan for an hour-long Scottish evening bulletin was rejected by the BBC in 2006.

Paul Holleran, Scottish organiser of the National Union of Journalists (NUJ) said: "It's a kick in the teeth for the Scottish management of the BBC.

"It's struggling at the moment and is under resourced.

"It's a real blow to TV production in Scotland and is a missed opportunity."

He added: "We've asked for BBC Scotland to get a higher proportion of spending in Scotland based on the licence fee raised.

"We and the BBC Scotland management have put forward a budgetary bid for an expansion of current affairs and for money to commission writers for music and drama programmes.

"But we're expecting an announcement on Thursday at the Culture Committee that will fall far short."

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Joan McAlpine, the SNP MSP who convenes the Scottish Parliament’s Culture, Tourism and External Affairs Committee, said: "A Scottish Six would provide a major jobs and investment boost north of the border and ensure that Scotland gets a much fairer share settlement from the BBC in London.

"The publicly-funded broadcaster risks being left behind by its commercial rivals who are already exploring similar formats.

"I look forward to discussing these issues with Lord Hall when he appears before the Committee this week – but he is going to face some extremely difficult questions if this is what he is coming to say."