Quebec Health Minister Yves Bolduc says it's unacceptable that inmates at the Salaberry-de-Valleyfield Detention Centre received swine flu shots before some people in the general population.

Bolduc blamed Tuesday's error on regional health authorities who misread provincial regulations governing vaccination schedules, Bolduc told the legislature on Wednesday morning.

The regional health board in Valleyfield, southwest of Montreal, admits it made a mistake in inoculating 51 inmates at the jail.

They received swine flu vaccinations on Tuesday morning while 10 others refused to be vaccinated.

Stephane Lemaire, president of the province's prison guards' union, said he was shocked to see inmates vaccinated before prison guards.

"We were outraged by the situation. It cannot happen again," he told CTV News in a telephone interview.

He said it's unacceptable for prisoners to be getting swine flu shots when ordinary Quebecers are being denied the vaccination because they aren't on a priority list.

Many people waiting in line outside of vaccination centres on Wednesday agreed.

"What you just told me made me really mad," said one woman, after learning about what happened.

"We have to wait to get our vaccine shots and they got theirs already - and they're in prison," said one frustrated man.