Media playback is unsupported on your device Media caption RHI scandal: Sinn Féin minister 'told nothing' of DUP plan

DUP ministers are working on emergency legislation to deal with the £490m RHI overspend - and it may be brought to a recalled assembly next week.

Economy Minister Simon Hamilton is seeking Sinn Féin's approval for the move which he said could reduce the projected £490m overspend to "zero".

But the Sinn Féin finance minister said he was "bemused" that the DUP announced it to the media before talking to him.

"The DUP are in a hole and should stop digging," Máirtín Ó Muilleoir said.

The Renewable Heat Incentive (RHI) scheme was set up in 2012 by Arlene Foster, more than three years before she became first minister and leader of the DUP.

It is understood the legislation aims to reduce the tariffs being paid to about 1,800 RHI claimants and will also introduce tiered payments to reduce the ovesrpend.

'Preferred option'

As a result, the green energy scheme's overall costs over 20 years would fall to within the £660m of funding to be allocated directly from Westminster, with no financial burden on the Stormont Executive.

Speaking on the BBC's Evening Extra programme, Mr Hamilton said he has been working very closely with his party leader on a plan which "will significantly reduce the cost of the RHI scheme on the Northern Ireland budget".

Image copyright Pacemaker Image caption First Minister Arlene Foster and DUP Economy Minister Simon Hamilton have been working on a plan to "reduce the cost to the Northern Ireland budget to zero"

"Arlene and I have agreed on a preferred option which I will want to discuss with executive colleagues, including the [Sinn Féin] finance minister, and also then bring to the assembly for approval an option that would, in effect, reduce the cost to the Northern Ireland budget to zero".

'Architect of RHI'

Shortly after the announcement, Mr Ó Muilleoir issued a statement saying: "I am bemused at the trailing in the media of a DUP 'plan' to resolve the RHI debacle when not one scrap of paper detailing this 'plan' has been received by the Department of Finance.

"I am alert to the dangers of allowing the person who was the architect of the RHI scheme - the DUP leader - to come up with a solution to this debacle. That is why I will ensure my officials rigorously test any plan which comes from the DUP.

"I will be guided solely by what is in the interest of the public purse."

Mr Muilleoir told BBC News NI his role as finance minister was not to "mark the homework of the first minister" but to "defend" public finances and "force the Department of the Economy to get its act together".

His statement added: "They should share any 'solution' they have now with the Department of Finance. In particular, the Department of the Economy should reflect on the fact that my department has flagged up concerns about the post-November 2015 tariff which they are suggesting will shortly apply to all businesses using the RHI scheme."

Analysis - BBC News NI business correspondent Julian O'Neill

An earlier idea, of closing the scheme entirely and paying compensation, has, at this stage, been discounted.

The BBC understands the DUP wants the executive to endorse the idea under emergency procedures this week, paving the way for a potential early recall of the assembly next week when the legislation would be introduced for a vote.

Legal advice has been taken.

One source said they believed the move was permissible, but did not discount the possibility of a legal challenge.

Earlier, Sinn Féin said they still want Mrs Foster to step aside while any investigation into the failings around the scheme gets under way.

Mrs Foster and DUP deputy leader Nigel Dodds held talks with Deputy First Minister Martin McGuinness and Sinn Féin's Health Minister Michelle O'Neill on Wednesday.

Mrs O'Neill said her party had drafted its own proposed terms of reference for an investigation.

"These will ensure a robust, time-framed, independent investigation with powers to compel witnesses and subpoena documents," she said.

"This investigation will be led by a judicial figure.

"We have given these terms of reference to the head of the civil service and to the DUP."

Sinn Féin has also held talks with Northern Ireland Secretary James Brokenshire.

The party said the terms of reference drawn up by the head of the civil service for an investigation into the RHI debacle were short of what was required.