The Fiji Islands Council of Trade Unions (FICTU) is planning legal action against the interim administration if it decides to replace union members when they go on strike.
The Fiji Times quotes the council's general secretary, Attar Singh, as saying any moves to replace their members would be viewed as illegal.
Mr Singh says if the strike goes ahead it will be a legal strike and no employer, not even the government, can bring in any other workers.
The general secretary of the Fiji Nurses Association, Kuini Lutua, says it is the right of every citizen to demand to be treated by a registered nurse.
She says a student nurse is required by law to work only under the supervision of a registered nurse and if retired nurses are brought back, they will need to undergo a refresher course.
The government has been talking of bringing in retired teachers and nurses to fill in for those who go on strike.