The union claims Doncaster & Bassetlaw Teaching Hospitals NHS Foundation Trust has threatened to fire and rehire the nurses on new contracts stipulating they must work part-time in Doncaster if they refuse to transfer voluntarily.
The proposals have already led to four members of staff leaving Bassetlaw ICU for other units, Unite adds.
Unite general secretary Sharon Graham said: ‘An NHS trust should not even be thinking of fire and rehiring staff – it is an abhorrent practice that should be banned outright.
‘The trust's threats have simply strengthened the nurses' resolve to stop Bassetlaw's residents being deprived of a critically important health resource. They have Unite's full support in taking strike action.'
In response, the hospital said the plan is about 'skills, competencies and safety'.
Chief nurse at Doncaster and Bassetlaw Teaching Hospitals, Karen Jessop, said: 'We understand that change is difficult, however this is about doing the right thing for our patients and securing the future of critical services locally.
'The Intensive Care Unit at Bassetlaw Hospital sees fewer critically ill patients than Doncaster Royal Infirmary, meaning clinicians at the latter manage more complex cases daily. By rotating our ICU clinicians across both sites, we ensure they maintain the skills and experience needed to provide safe, high-quality care — wherever it's needed.'
However, Unite refutes that nurses are at risk of being deskilled because of a lack of exposure to level three patients - those who are ventilated or have multiple organ failure.
The union says the trust's data shows that there has not been a downward trend, and that per capita, nurses at Bassetlaw have a similar or higher exposure to level three patients than nurses at Doncaster.
Unite regional officer Chris Rawlinson added: ‘The trust's plan is entirely unreasonable. They add at least an hour and half commute for those who drive and three hours for those who use public transport.
‘This is on top of the 13 hour shifts the nurses already work – risking burnout for them and needlessly endangering patient safety due to staff exhaustion.
‘Furthermore, this is a clear attempt at decommissioning by stealth – with the real risk that Bassetlaw patients in urgent need of an ICU will end up having to travel 20 miles to Doncaster to get to one. The trust must row back.'
Dates for strike action will be scheduled in the coming weeks if the dispute is not resolved, the union said.