It criticises the Irish state's failure to protect vulnerable people, including children, from exposure to sexual exploitation and forced labour and singles out the fishing industry for special mention.
Commenting on the report, Ken Fleming, ITF co-ordinator for Ireland and Britain, said: "This confirms our own findings and those of the Joint Oireachtas Committee on Business, Enterprise and Innovation on the scale of the problem in the Irish fishing industry.
"It is heartening that a completely independent international body has validated our own findings by its' decision to downgrade Ireland's ranking in this vitally important sector where human rights are under constant attack by unscrupulous and unconscionably greedy employers.
"The continuing failure of the Irish state to effectively enforce its own laws or heed warnings by organisations such as the ITF and the Joint Oireachtas Committee has left us with no option but to initiate proceedings against the government in the High Court, which are due to be heard in the near future."
The report can be found here.