NORTHERN Ireland’s Deputy First Minister Martin McGuinness has called on First Minister Arlene Foster to “step aside” to allow an investigation into a controversial green energy scheme.

McGuinness said he told her over the phone he was seriously concerned about allegations around the eco-friendly initiative that has left Stormont facing an estimated £400 million overspend.

The credibility of Northern Ireland’s peace-building, power-sharing political institutions is being “undermined” by the Renewable Heat Incentive scheme row, he said.

“This includes allegations from a former Democratic Unionist Party minister that there was corruption,” he said.

McGuinness said he told Foster that taxpayers’ money has been wasted in this scheme, which needs to be retrieved, and the only way to establish the truth, and rebuild trust in the power-sharing executive, is to set up a fully independent investigation.

“In addition, I also said that, in the public interest, she should stand aside from the role as First Minister while that investigation is under way and at least until an initial assessment had been concluded into the veracity of all the allegations,” he added.

“That is what I would do if I was in this situation.

“I asked the First Minister to take the time and consider this suggestion carefully.”

The “cash for ash” controversy escalated on Thursday when former DUP Economy Minister Jonathan Bell broke ranks to level a series of explosive claims against Foster and party advisers.

But Foster’s Democratic Unionist Party has insisted she will not step aside.

A party spokesman said the First Minister will “not be stepping aside” but instead is “focused on ensuring the full facts about this issue emerge”.