DUP peer and MLA, Lord Maurice Morrow, has been criticised by his UUP counterpart for making a joke about the botched RHI scheme, which is costing tax payers £85k a day.
"He should catch himself on," said South Tyrone UUP MLA Rosemary Barton.
Lord Morrow was caught on video laughing about the scheme with former First Minister Arlene Foster as the pair lodged their election nominations on Friday in Omagh.
He was heard to say: "It's hot. Yes, the boilers are all working," while laughing.
Mrs Foster replied: "Stop it, stop."
Following Lord Morrow's comments, which she has dubbed "shameful", Mrs Barton said: "The RHI debacle will cost £85,000 every single day between now and the election. The financial impact on Northern Ireland's finances cannot be underestimated yet here we have Lord Morrow of the DUP making frivolous remarks about it with his party leader, Arlene Foster, at their nomination for that same election.
"He should catch himself on. If it hadn't been for his party's handling of the RHI debacle and Sinn Fein's opportunism, we wouldn't be having these elections which will cost the taxpayer at least another £5 million.
"The DUP/Sinn Fein Executive were the architects of this scandal. Maybe it's time Lord Morrow and his colleagues dropped their Stormont Castle mindset and tried to understand the consequences of their actions given the financial difficulty some people in Fermanagh and South Tyrone are having when trying to heat their homes."
Lord Morrow has been contacted for comment.