A report on people trafficking for cannabis cultivation claims Ireland may be imprisoning victims of slavery.

The report, published today by the Migrant Rights Centre Ireland, is part of a major European project on trafficking for forced labour.

It says there is evidence that vulnerable people may have been trafficked into Ireland and forced to work in cannabis growhouses.

The MCRI says people have been found malnourished and terrified in houses locked from the outside, yet they were still treated as criminals and given heavy prison sentences.

Spokesperson Grainne O'Toole said the victims of forced labour need to be taken into protective care.

Speaking on RTÉ's Morning Ireland, she said there are potentially victims of trafficking sitting in prison whose cases need to be assessed.

"The reason the slavery exists is it's profit driven, so what's happening here is we know that cannabis production is a very profitable and lucrative business for criminal gangs.

"But it's making it more lucrative for them if they can basically put slaves into cannabis grow houses to do their dirty work for them, then these people are serving the time, so it's risk free for them", she said.