Siptu says between 15-hundred and two thousand health workers who signed up to be "On Call for Ireland" were handed agency contracts with inferior terms and conditions.
The trade union says it's been contacted by a number of workers hired under the scheme.
It says the contracts don't include death-in-service benefits which could amount to up to two years' salary for a worker with a direct state contract, or Covid-19 leave pay.
The Cathaoirleach of Castlebar Municipal District Michael Kilcoyne raised this issue with HSE West Management last week. He asked for details on the number of staff that have been hired by the HSE at Mayo University Hospital, as distinct from agency staff, since Minister Harris made what he termed “his emotional On Call for Ireland last March”.
HSE West Management said they did not have the figures to hand but said they would get back to him with a response.
Siptu's Paul Bell says agency staff are taking all the same risks as those with hospital contracts - and should get the same treatment.