The Government has accused Iran of failing to protect Christians under international law.
In a statement at the UN, UK Ambassador Miriam Shearman highlighted the arbitrary way in which Iran detains and mistreats Christians.
It is illegal in the Middle-Eastern state to preach the Gospel or convert to Christianity, and Christians are at constant risk of arrest and imprisonment.
The Ambassador accused Iran of torturing its prisoners and failing to allow them their own lawyers and an impartial trial.
She said: “We remain deeply concerned by Iran’s failure to uphold international legal obligations, and its arbitrary detention of citizens and dual nationals arrested on unclear charges, denied due process and subject to mistreatment.”
Iran is one of the worst countries in the world for the persecution of Christians.
Open Doors, a charity which researches and ranks the countries where Christian persecution is at its worst, placed Iran at number 9 on its World Watch List, ahead of both India and Syria.