Christian Solidarity Worldwide (CSW) has received reports that a pastor has been arrested for a second time on August 17.
Abdolreza ‘Matthias’ Haghnejad, a pastor in the evangelical Church of Iran denomination, was reportedly re-arrested by Iranian authorities in Rasht whilst making a pastoral visit.
His family are in the dark about why he has been arrested and his whereabouts.
There are also concerns that he does not have access to an attorney.
Pastor Haghnejad was arrested previously in 2006. Earlier this year, he was charged with activities against the order and rounded up by authorities along with 10 other members of his denomination. He was released when the authorities dropped the charges.
Last month, a Christian man and woman were detained in Iran. The man was released but the woman, Leila Mohammadi, was arrested and is believed to be behind bars in Evin prison.
CSW’s Advocacy Director Andrew Johnston said: "It is vital that the Republic of Iran ensures due process and ends this practice of incarcerating persons simply on the basis of their faith as this is in clear violation of the International Covenant on Civil and Political Rights (ICCPR).
"Those who, like the pastor, have been arrested must either be charged and tried in a timely manner or released, and all detainees must be allowed contact with their families and lawyers.”
Earlier this month, the authorities confiscated 6,500 Bibles as they were being transported in the north-western province of Zanjan.
CSW reports that Dr Majid Abhari, adviser to the social issues committee of the Iranian parliament, declared that Christian missionaries were attempting to deceive people, especially the youth, with an expensive propaganda campaign. He also indicated his belief that all religions are strengthening their power to confront Islam.
Rhetoric has turned increasingly anti-Christian in recent months, with one official saying Christians are like the Taliban and "parasites".
Mr Johnston said the latest arrests and hostile rhetoric were "extremely concerning".