Saeed Abedini is serving an eight year prison term for helping to Christians set up home churches to pray together.
New claims this week suggested he was being tortured in prison and new charges may be brought against him. His wife says he told her about the ordeal during a visit.
Christians in several countries are holding prayer vigils for Abedini to mark the third anniversary of his imprisonment.
Premier's been told the pastor faces regular beatings behind bars and on one occasion had to be taken to hospital because he was so badly injured.
Medics at the hospital refused to treat him because he was Christian and 'unclean', Premier understands.
Pastor Saeed's wife, Naghmeh Abedini said intelligence officers repeatedly used Taser electric shock guns on him.
Mrs Abedini said he was tortured during an interrogation session on Tuesday and is in need of medical treatment.
"When will this nightmare end?" She said.
"Saeed is not a criminal. Being a Christian and motivated by Christian values to help the poorest and most needy children in Iran should be seen as good for the Iranian society.
"Hearing that yet again the hardliners in Iran are trying to fabricate evidence against my husband and that he was abused and Tasered is almost too much to bear."
She said he had been threatened with death by prisoners who are members of Islamic State and al-Qaeda.
The Muslim convert has been promised his freedom if he recants his faith. He and his wife are members of the evangelical Calvary Chapel in Idaho.
Iranian President Hassan Rouhani is due to address the UN General Assembly in New York next week.
"Please pray that the Government of Iran will show clemency to Pastor Saeed and release him," said Paul Robinson, the Chief Executive of Release International, which supports persecuted Christians around the world.
"Pray that President Hassan Rouhani will heed calls for greater religious freedom in his nation.
"Pray for the release of all those who are imprisoned for their faith in Iran. And pray that their witness will touch the hearts of their guards so they are treated with dignity."
Listen to Premier's Antony Bushfield speaking to Release spokesman Andrew Boyd:
