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.

Mr 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 £400m (€477m) 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.

In a statement, a spokesman for the DUP says the First Minister will not be stepping aside and is focused on ensuring the full facts about the issue emerge.