Last week Healthcare Republic reported that the NMC was taking the action to target nurses or midwives whose registration had lapsed within the previous four years.
Gail Adams, Unison's head of nursing, said: ‘At a time like this we need all hands to the pump to cope with a swine flu pandemic.
‘We need to make it easy for people to get back to work and it is hardly fair to make them pay a registration fee.
‘Unison believes that nurses, doctors, paramedics and other health workers, who answer the NHS' call for help during the pandemic, should not have to pay the price for doing so.'
Readmission costs £76 with a £76 retention fee at the end of the first and second years of the registration period.