The Irish Medical Organisation has said agreement will not be possible on new consultant contracts by next Tuesday.
The Government had set Tuesday as the deadline for an agreement to be made.
The IMO said that any attempt by the Minister for Health, Mary Harney, to act unilaterally in appointing new consultants under imposed terms from next week would be confrontational.
Fintan Hourihan of the IMO said if this occurred the organisation would ask that its members not apply for the jobs or co-operate with interview panels.
Mr Hourihan was speaking in advance of the IMO's annual three-day conference which begins in Killarney, Co Kerry today.
Health employers are offering consultants who agree to work full-time in the public system a salary of €205,000 a year.
But doctors are unhappy with limits on private practice, and a so-called gagging clause to stop them speaking out in public about service failures.
Ms Harney had told the consultants that if there was no agreement on new contracts by Tuesday, the Health Service Executive will begin advertising for around 350 new consultant posts on its terms.
The minister will address the conference tomorrow afternoon and appears heading for direct confrontation with another group of health professionals following the nurses' work-to-rule dispute and the row over Cork University Maternity Hospital.
