United Future leader Peter Dunne has compared Australia's detention centres to concentration camps and says the Government's ministers are "villains" because of their poor treatment of detainees.
Mr Dunne made the comments in a regular blog "Dunne Speaks", and has repeated them in Australian media.
He said that in the uproar in Parliament this week over Mr Key's comments about rapists, the issue of detainees in Australia's offshore camps had been pushed into the background.
Mr Dunne said the some of them had committed unspeakable crimes, but they still retained the same basic human rights.
However, the "modern concentration camp" approach taken by Australia meant the detainees were now worse off than they were in prison.