The prospect of new Northern Assembly elections and the collapse of Stormont appeared to draw closer on Thursday night after Sinn Féin dismissed DUP proposals to deal with the “cash for ash” heating scheme fiasco.

The state-funded renewable heat incentive scheme (RHI), which has become known as “cash for ash”, was supposed to cover a proportion of the cost businesses had to pay to run eco-friendly boilers, but the subsidy tariffs were set too high and without a cap, so it ended up paying out significantly more than the price of fuel.

This enabled applicants to “burn to earn”, in that it allowed them to both get free heat and make a profit.

Ms Foster oversaw the inception of the RHI scheme during her time as minister for the economy.

She has steadfastly refused to step aside amid criticism of the scheme and has claimed that some of those calling for her head are motivated by misogyny.

Sinn Féin Minister for Finance Máirtín Ó Muilleoir and the DUP Minister for the Economy Simon Hamilton met on Thursday afternoon for a “clear the air” meeting on how to significantly limit the projected £400 million (about €469 million) overspend on the scheme.

Mr Hamilton had said on Wednesday that he and his officials had devised a plan to bring the additional cost of the scheme to “effectively zero”.

However, after Thursday’s meeting, Mr Ó Muilleoir criticised what he described as the “sticking plaster” proposals and again warned that the Northern Executive and Assembly would fall if DUP leader Arlene Foster did not step aside as First Minister.

Emergency proposals

Mr Hamilton had hoped to present his emergency proposals on the RHI scheme to a special meeting of the Assembly next week and to brief the Northern Executive on his plan.

Mr Ó Muilleoir said that, based on the proposals he had heard from Mr Hamilton, there was “no basis for the [early] recall of the Assembly or the Executive” from their Christmas recess.

“After seven months, the DUP Economy Minister outlined interim measures which are little more than a sticking plaster approach. That is not good enough,” said Mr Ó Muilleoir.

“There is no long-term plan to tackle the RHI debacle and its potential loss of hundreds of millions of pounds to the public purse.

“I was disappointed at the failure of the Economy Minister to present a plan despite this being heavily trailed in the media,” he said.

“Unlike previous Finance Ministers who dealt with this scheme, I will work to safeguard the public purse.

“We need to see detailed proposals and ensure they are financially and legally sound, timely, at a zero cost, and protect against future abuse.”

Mr Ó Muilleoir also told the BBC that if Ms Foster did not step down pending an investigation into the RHI scheme that Stormont would collapse.

“I am forthright in saying if Arlene Foster does not step aside there is no way out of this impasse and these institutions will fall,” he said.