INTERNAL bust-ups and “dysfunctional” relationships among senior DUP figures have been exposed in the latest revelations around Stormont’s Renewable Heat Incentive scheme.

Ahead of what is expected to be a dramatic evidence session involving former minister Jonathan Bell at the public inquiry tomorrow, the senior civil servant who oversaw the scheme’s closure has catalogued a series of unedifying episodes that heap further embarrassment on Arlene Foster and her party.

Mr. Bell succeeded Mrs. Foster as economy minister in May 2015 as the green energy scheme she had overseen since its conception went way over budget.

He broke ranks at the height of the outcry over RHI, alleging that DUP special advisers had intervened to block curbs on the lavish scheme – a claim denied by those involved.

Evidence from former Department for the Economy permanent secretary Andrew McCormick shows how there was “tension” between Mr Bell and his special adviser Timothy Cairns. …

The inquiry has even heard allegations that the former Strangford MLA tried to break Mr Cairns’s finger and swung a punch at him.

It has also been claimed that Timothy Johnston, now the DUP’s chief executive, was involved in the decision to delay the imposition of cost controls on RHI.

In written evidence given by Mr. Cairns, Mr Johnston is said to have told Mr. Bell’s adviser that cuts to the generous tariffs would not be introduced and that he should work with fellow DUP special adviser Andrew Crawford “at looking into an alternative”.

Mr McCormick’s evidence claims the DUP was protective of Mr Johnston and sought to “deflect or discredit” any reference to Mrs. Foster’s then adviser.