A total ban on so-called gay conversion therapy would breach the constitutional right to religious freedom, the Council of State has said in an opinion.

A coalition of six parties drawn from the cabinet and the opposition put a bill before parliament last February outlawing the practice, with fines of up to €22,500 or a year in prison for first offenders.

MPs said the move was designed to protect children and vulnerable adults from the effects of the therapy. It would not only outlaw the practice of conversion therapy, but make it illegal to offer it.

The Council of State, which vets all proposed laws before they are enacted to check if they are compatible with existing legislation and legally sound, said it understood the reasoning behind the ban, but the therapy was often carried out within strict Christian communities.

It also questioned how the law was supposed to distinguish between people who were coerced into undergoing conversion therapy and those who did so voluntarily.

The council said a ban on offering the therapy risked being unworkable because practitioners would simply describe their treatment differently. It also pointed out that intrusive forms of conversion therapy were already covered by laws against discrimination and enforced medical intervention.