Renewable Heat Incentive scheme: Experts investigate whistleblower's 'green heating fraud' claim
Experts have begun checking whether businesses which took advantage of a lucrative green energy scheme have been defrauding the system.
A whistle-blower claimed some clients intended to earn hundreds of thousands of pounds in subsidies.
The plan involved installing wood boilers to heat empty buildings.
Auditors said the scheme, which had been over generous and open to potential fraud, left taxpayers with a bill of at least £150m over five years.
The Department of the Economy said it had no plans to publish an internal review of how the scheme had been run.
The review was commissioned by the department and the regulator, the Office of Gas and Electricity Markets (Ofgem), which helped administer the programme in Northern Ireland.
A separate independent audit has been commissioned by the economy minister, Simon Hamilton.
It is expected to report in the Autumn.
The renewable heat incentive scheme was introduced to encourage firms to switch from oil or gas to wood burning boilers.
It was part of a Northern Ireland Executive initiative to meet renewables targets.
A Northern Ireland Audit Office report in July 2016 found it had been overly generous and not properly controlled or monitored.
There was no cap on the subsidy payments. The more heat you generated, the greater the subsidy you were paid.
More than 2,000 applications for the subsidy have now been reviewed. A percentage of them are now being visited and checked.
Any abuse of the scheme could lead to disqualification or potential prosecution. Participants will have to prove they installed the wood boilers to replace existing forms of heat.
It has been claimed that some were put in for the sole purpose of claiming the subsidy.