The Irish Medical Organisation (IMO) has said it is advising its members not to accept any patients using the new "medical visit cards".
Dr Martin Daly, Chairman of the national GP Committee of the IMO said the organisation had sought legal advice on the proposed cards.
According to Dr Daly, legal advice to the IMO was that the changes proposed under the new Health Bill represent "a material change to the terms of the GMS Contract held by General Practitioners and that any such changes will require to be negotiated and agreed with the IMO."
Ms Harney announced last November that she planned to issue an extra 30,000 medical cards this year as well as a new type of card to 200,000 people that would allow them to visit their GP for free.
However, these doctor-only cards would not cover any drugs the holders might need to get from their pharmacy.
"The IMO has sought urgent negotiations with the Tánaiste and Minister for Health & Children and the Interim Chief Executive of the Health Service Executive in respect of the proposed changes," according to Dr Daly.
"In the meantime, the IMO is advising all GMS Doctors not to 'sign on' any patients under the new provisions pending the conclusion of negotiations with the IMO and a subsequent ballot of our members," said Dr Daly.
The Labour Party's Liz McManus said the Government's plan was degenerating into "another shambles" and the Tánaiste would have to take "full responsibility" for what she called the "lack of planning" for the scheme.
Ms McManus called on the Government to scrap the card proposal and to extend full medical cards to another 200,000 citizens.
Fine Gael health spokesman Liam Twomey said the IMO boycott is the result of a failure on the part of the Tánaiste to engage properly with the organisation.
"I think the Tánaiste is in danger of snatching defeat from the jaws of victory here, and I would urge her to respond to any reasonable IMO requests for discussion now so that we can see progress at the earliest opportunity."
