Patient safety may be compromised in public hospitals because of the appointment of doctors without specialist training to consultant positions.
The Irish Hospital Consultants Association has criticised the practice saying quality of care is being affected.
The HSE has confirmed that 128 doctors who are currently working as consultants in public hospitals are not on the specialist register of the Medical Council.
Details of the numbers were provided to the Sinn Féin health spokesperson Louise O'Reilly.
Speaking on RTÉ’s This Week programme, Ms O'Reilly said it was unacceptable and that it was unfair to the public.
In a parliamentary reply to her, the HSE acknowledged the appointments by public hospitals were in breach of regulations.
A report commissioned by the HSE said there were "significant risk issues" arising from the poor compliance by hospitals to the national guidelines for employing consultants.
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Ms O'Reilly said she believed the numbers provided by the HSE needed further investigation as there may be doctors who are about to become eligible for similar appointments even though they are not on the specialist register.
The HSE confirmed 58 of the total were made consultants before regulations were changed in March 2008 and the other 70 were appointed since then.
The Sinn Féin health spokeswoman said people attending public hospitals were entitled to be assured that doctors presenting as consultants were actually fully qualified.
Speaking on the same programme, Dr Tom Ryan, President of the Irish Hospital Consultants Association, said the practice of making these appointments gave rise to serious issues of patient safety and care.
He also called for further investigation of the HSE figures released to Ms O'Reilly.
The Minister for Health Simon Harris said he expects the HSE to comply with statutory and policy requirements when filling consultant posts.
The HSE said it is working to identify all the posts involved and to ensure regulations are enforced by the hospitals when making consultant appointments.