Sinn Fein wanted Attorney General John Larkin to appoint a foreign judge to conduct a limited investigation into the RHI scandal

The development, which comes after weeks of Sinn Fein flip-flopping on whether the party supports a full public inquiry into the £500 million debacle, would appear to set back the DUP-Sinn Fein plan for addressing an issue which has infuriated the public.

Although senior Sinn Fein figures Conor Murphy, Mary Lou McDonald and Declan Kearney have called for a full public inquiry, the party has now settled on a less far-reaching and faster form of inquiry.

A Sinn Fein motion to be debated at Stormont on January 16 calls for an “independent, time-framed, robust and transparent investigation”.

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Declan Kearney MLA.

The motion adds: “This investigation would be undertaken by an independent judicial figure from outside this jurisdiction and be appointed by the attorney general.”

On Tuesday Sinn Fein chairman Declan Kearney – who attacked what he termed “juvenile journalists” for raising questions about Sinn Fein’s stance (an apparent reference to the News Letter) told the Nolan Show that the probe must have the power to compel witnesses and documents.

Sinn Fein has argued against a public inquiry under the Inquiries Act 2005 – something which would give the inquiry wide-ranging powers of compulsion and sanctions for those who disobey the inquiry.

Declan Kearney MLA.

But Attorney General John Larkin’s office said that he has no power under the Inquiries Act to set up an investigation and that there is no other mechanism whereby he could set up an investigation with powers of compulsion.

The News Letter asked the Attorney General’s Office whether Mr Larkin has any power under the Inquiries Act 2005 to set up an investigation and whether – in the absence of any powers from that legislation – he could otherwise set up an investigation with powers to compel witnesses and documents.

A spokesman for the Attorney General’s Office responded: “There’s nothing in the Inquiries Act which permits the attorney to even call an inquiry. It’s purely down to ministers and specifically mentions ministers only.”

The spokesman added that “there is nothing else that would even give him remit in the 2002 legislation which set up the attorney general which would allow him to call any other powers or inquiries”.

Meanwhile, last night Sinn Fein health minister Michelle O’Neill issued a statement in which she pointedly made reference to the need for the inquiry to be able to compel witnesses and papers – something which to date Sinn Fein statements have not specified.

Ms O’Neill said: “We cannot have a process that long fingers the issue and results in tens of millions of public money being squandered on top of the hundreds of millions already at risk.

“There is a need to get to the bottom of the RHI scandal and to hold those responsible to account. We need to put in place a process, which gets to the facts quickly, effectively and with minimum cost to restore confidence in the political process.

“Sinn Féin believes the quickest and most cost-effective way to achieve this is a thorough, independent investigation which is robust, transparent, time framed and led by a senior judicial figure from outside the jurisdiction and with the power to compel witnesses and documents.”

But TUV leader Jim Allister accused Sinn Fein of “bluster” and said that anything less than a full public inquiry “provides a soft landing for its DUP partner, which, I suspect, is Sinn Fein’s real intent”.

Mr Allister surmised that “as yet unseen concessions have probably been extracted, or are being negotiated, as the price of blocking a proper public inquiry”.

He added: “No matter how it is dressed up a mere ‘investigation’ will be a vehicle for cover-up and whitewash. Only a public inquiry under the Inquiries Act 2005 would have the essential powers to compel witnesses and the production of documents. An ‘investigation’ would be held behind closed doors and be a toothless tool for the powers that be – a bit reminiscent of the farcical ‘investigation’ Peter Robinson had conducted into his difficulties, which was never published, but resulted in him self-proclaiming vindication.