Nine potential cases of fraud out of almost 2,000 applications to Stormont's botched energy scheme have been uncovered to date.
Energy watchdog Ofgem confirmed that its counter fraud team was looking at nine cases involving potential suspected fraud relating to the Northern Ireland Renewable Heat Incentive scheme.
The botched scheme is set to cost Northern Ireland’s taxpayers an extra £490m after it went vastly over budget.
The nine cases of potential fraud being investigated by Ofgem range in cost from £48,000 to £2.5 million.
Ofgem has been carrying out site visits in a bid to identify fraudulent behaviour.
The watchdog insisted it took a "zero tolerance approach to fraud".
A spokesman said: "Our counter fraud team is looking at nine cases involving potential suspected fraud relating to the Northern Ireland RHI.
"We have robust systems in place to monitor compliance with the scheme regulations, including site inspections, and take a zero tolerance approach to fraud.
"Our dedicated counter fraud team works to prevent, deter and detect fraud across the schemes we administer on behalf of the government and investigates all instances of suspected fraud, including acting upon referrals from third parties.
"Where appropriate we refer such cases to the police through Action Fraud."
Ofgem has not yet referred any cases to the Police Service of Northern Ireland.
The PSNI has already said that it is in contact with Ofgem and the Department for the Economy over the referral of suspected fraud cases at the earliest opportunity.
PSNI Detective Chief Superintendent Tim Mairs said: "To date, both bodies have confirmed to me that they have not identified any cases meeting this criteria."
The RHI scheme was intended to increase the creation of heat from renewable sources.
However, businesses have been receiving more in subsidies than they are paying for renewable fuel and the scheme became heavily oversubscribed.
The fallout from the scandal surrounding the scheme resulted in the resignation of Sinn Féin's deputy first minister, Martin McGuinness, the collapse of Stormont's institutions and the calling of snap elections on 2 March.
Retired appeal court judge Patrick Coghlin will chair a public inquiry into the botched energy scheme.