More than 60 consultants have been told they will have to stop double-jobbing in both St Vincent's public and private hospitals from the end of March.
The St Vincent's Healthcare Group, which includes both hospitals, has been instructed by the HSE that the arrangement permitting them to practise in the private hospital is outside the limits of the doctors' contracts and must change.
It is among a series of changes, including an end to top-ups for its senior managers, which the group must comply with in little over two months.
A spokesman for the Health Service Executive (HSE) said there could be no special arrangements for these consultants in St Vincent's public hospital which are outside their contracts.
The consultants are on type B contracts, which allow them to treat both public and private patients.
However, under the terms of their contract, these private patients must be in facilities within the public hospital.
The public and private hospitals in St Vincent's are separate institutions, even though they are on the same campus and under the umbrella of the St Vincent's Healthcare Group.
The ability of consultants to also treat patients in the private hospital has boosted their personal incomes and is also a major financial asset for the private hospital.
A HSE spokesman said that the public hospital must end the arrangement as part of its service level agreement which it signs with the HSE in return for its annual budget allocation.
The doctors would still be able to treat private patients in the public hospital but they would not have access to the same number of beds.
A spokesman for St Vincent's Healthcare Group declined to comment yesterday and said he would not be adding to the evidence given to the Dail Committee on Public Accounts by hospital chief executive Nicholas Jermyn.
Mr Jermyn and members of the board were before the committee to answer questions on salary top-ups and other potential conflicts of interest.
Mr Jermyn, who is paid a combined salary of nearly €300,000 in public and private payments, is to step down from the public hospital and remain as group chief executive.
The most recent Healthstat statistics, which measures activity in public hospitals, show that more private patients are being treated in St Vincent's public hospital than public patients.