Northern Ireland's Public Accounts Committee is continuing its investigation into a £1.2 billion government-funded renewable energy scheme that could involve an overspend of hundreds of millions of pounds. 

The North's Economy minister has warned that criminal prosecutions should be brought against anyone who abused the scheme.

Simon Hamilton rejected claims his predecessors were "asleep at the wheel" when the controversial Renewable Heat Incentive (RHI) was rolled out by the former Department of Enterprise, Trade and Investment (DETI).

Northern Ireland First Minister Arlene Foster held the DETI portfolio at the time.

Ulster Unionist Party leader Mike Nesbitt has called it "the biggest financial foul-up in Northern Ireland's history".

The RHI aimed to cut the cost of green energy to encourage people off fossil fuels but ended up landing ministers with a massive overspend.

It encouraged the installation of costly eco-friendly heating systems by paying a tariff per kilowatt of heat burned over a 20-year period.

However, unlike in the rest of the UK, in Northern Ireland no cap or payment tier system was placed on the money that could be claimed in proportion to the size of boiler and the hours it was operated.

That effectively enabled a business to burn unnecessary heat 24 hours a day, seven days a week just to make money.

Management of the scheme is currently being examined by MLAs on Stormont's public accounts committee.

Mr Nesbitt said the scandal is "up there with NAMA" and that Ms Foster "should consider her position".

Mr Hamilton was questioned about the initiative during Question Time at the Assembly yesterday.

Mr Hamilton said: "I am absolutely adamant that where there is proof and evidence of abuse of the scheme, that appropriate action including, if required, criminal proceedings should begin against anybody who has abused the scheme or defrauded the scheme."

Mr Hamilton said new measures were being put in place to mitigate any costs to the public purse and revealed that a consultation is expected to be brought forward early next year.

Overall, more than £1bn of public money will be paid by 2036 to Northern Ireland-based businesses which signed up to the scheme.

Mr Hamilton said previous ministers had been ill-advised by policy officials.

"It is very clear to me that the ministers followed all advice given to them and because that advice was wrong; it was based on bad grounds the scheme was badly designed," he said.

"Nobody has denied, least of all me that this was shocking and we need to deal with those problems."