Northern Ireland's top auditor has called for an independent investigation into allegations that another green energy scheme here is open to exploitation.
Kieran Donnelly was responding to claims in a BBC investigation into renewables in Northern Ireland
BBC File on 4 looked at payments to anaerobic digesters as part of that investigation.
Mr Donnelly is the Comptroller and Auditor General for Northern Ireland.
The programme suggested there were up to eight "phantom plants" which used a postcode loophole to attract the maximum level of subsidy.
It was alleged they appeared to exist in name only for the purpose of drawing down the cash, which is paid out of consumers' electricity bills.
The documentary highlighted one company. It denied the allegations and said it had complied with the regulations.
Anaerobic digesters use organic material like slurry and silage to produce methane gas which is then burned to produce renewable electricity.
A 500Kw capacity plant can earn up to half a million pounds a year in subsidy.
Mr Donnelly said he had been alerted to the allegations in the programme by the Department for the Economy which is responsible for the scheme.
He said it did not fall within his remit because the subsidy money was raised from a customer levy rather than paid out of the public purse.
"However from the allegations that I have been made aware of, it is clear that there needs to be an independent investigation into this matter."
He said it was an issue that he intended to monitor closely.
The department said it was working with the Office of Gas and Electricity Markets (Ofgem) which administers the scheme on its behalf.
It said it was organising audits of any plants where it felt extra checks might be needed.
It said having been in contact with Ofgem it had established that not all the allegations had been "factually accurate".
It also said the rest of the programme's claims would be checked by Ofgem.
What is anaerobic digestion?
- Process by which micro-organisms break down biodegradable material in the absence of oxygen
- Organic material such as manure, crops, grass or slurry is put into large containers
- Once this material breaks down it produces biogas such as methane
- Methane can be converted and fed into the National Grid
The department has confirmed that there are 89 anaerobic digester plants in Northern Ireland.
It said 14 of the 89 plants have been audited, with further checks on others to follow.
It said it had been aware of planning and environmental issues around some, but had not received any allegations of abuse prior to those supplied to it by the BBC.
"As this is a live investigation it would be inappropriate to comment further," a spokesperson said.
Ofgem said postcode checks were just one in a series of controls before plants were accredited.
It said it couldn't comment on individual cases but it took allegations of this nature "very seriously".
A spokesman said if it found evidence of fraud it contacted the police, and also had the power to revoke or withhold the certificates issued to secure subsidy payments.