The DoH said the plans are meant to highlight whether a healthcare worker is likely to pose a threat to patient safety.
But in response to a DoH consultation, the MDU said it did not believe the move was the most effective way to enhance patient protection and may be open to legal challenge.
Dr Hugh Stewart, the MDU's head of case decisions, said the regulations were 'considerably flawed' and 'little more than a gossip's charter'.
He said: 'We have never been persuaded that passing on so-called soft information about doctors in the way proposed would add anything to the existing measures in place to protect patient safety.
'These regulations give relevant officers the power to pass on potentially damaging information about a doctor to other organisations and there is no appeals process if, for example, the doctor in question thinks there is a conflict of interest or unfair bias or just that the information is wrong.'
The MDU said there are already 'effective mechanisms' in place to provide information about doctors, such as the GMC register and the alert letters system.