The prospect of Stormont Assembly elections this year has been raised, as the 'cash for ash' controversy continues.

Sinn Féin yesterday turned up the heat on First Minister Arlene Foster of the DUP, saying going to the people is a real prospect if she does not stand aside while an investigation into the Renewable Heat Incentive scheme takes place.

The scheme was launched by Mrs Foster when she was enterprise minister, and offered subsidies to businesses switching to greener fuel.

When some were found to be heating empty warehouses, it emerged a lack of cost controls meant the more they burned, the more they earned from the public purse.

It is has been suggested that Northern Irish taxpayers could have to foot the bill worth hundreds of millions of pounds arising out of the RHI scheme.

Sinn Féin leaders, including Deputy First Minister Martin McGuinness, have called for Mrs Foster to temporarily step aside during the investigation.

Writing in An Phoblacht yesterday, the party's national chairperson Declan Kearney said: "The political process has now been dragged recklessly by the DUP – culminating with the RHI crisis – towards an unprecedented tipping point."

In an interview on BBC, he also raised the possibility that Assembly elections could take place if Mrs Foster does not step aside.

Belfast security correspondent Alan Murray says yesterday's 'dramatic language' from the Sinn Féin chairman could be a game-changer.

Speaking to Newstalk Breakfast, Alan explained: "If you had said to me before Christmas 'will there be an election in February, March?' I would have said 'I don't think so'.

"Yesterday changed that. You have to say you can't rule out the possibility of an election in February or March or April of this year," he suggested.