The Department for the Economy has been accused of losing control after the latest in a series of mistakes over payments to renewable energy companies.
There was outcry on Monday after it was revealed that £520,000 was paid out in March to wind turbine owners in error as part of the Small Business Support Grant scheme.
With the payments intended for businesses struggling during the pandemic, wind turbine owners were declared ineligible seven weeks after the money was automatically paid out.
Questions were also raised about whether owners of anaerobic digesters had benefited needlessly, with the Department for the Economy confirming yesterday that one payment of £10,000 had been made.
There is no suggestion any recipients acted inappropriately.
The department is now attempting the recoup the overspend "where possible" but has not ruled out the possibility that more businesses received payments in error.
SDLP energy spokeswoman Sinead McLaughlin MLA called on Economy Minister Diane Dodds "to get a grip". "There has been a spate of serious mistakes that have come to light over recent days," she said.
"There were perverse incentives in the Northern Ireland Renewables Obligations (scheme) promoting the use of less efficient smaller wind turbines, some of which were not even connected to the electricity grid.
"This led the Northern Ireland Audit Office to complain about the legislation, which they described as 'vague'.
"Then we find out that operators of wind turbines were paid grants that they shouldn't have received. All of this after the mess over the Renewable Heat Incentive (RHI).
"Meanwhile, businesses in desperate need of financial support are going without and are at risk of collapse. This is just not good enough.
"The Department for the Economy seems not to be under control. The minister and the permanent secretary need to get a grip and do so urgently."
TUV leader Jim Allister MLA questioned why the department had taken so long to disclose that an extra payment of £10,000 had been made to the owner of an anaerobic digester.
"I wonder, has this department learned nothing from RHI?" he asked when appearing on the BBC yesterday.