The ecumenical religious rights charity Christian Solidarity Worldwide said this week that Pastor Yousef Nadarkhani, of the Church of Iran, has been jailed for evangelising to Muslims.
In September Pastor Nadarkhani was sentenced to three years in prison but was released after posting bail, having already spent three years in Lakan Prison in the northern coastal city of Rasht.
He has now been returned to prison to serve the remaining 45 days of his sentence.
Meanwhile two other Christians from the Church of Iran were detained yesterday as part of a crackdown on house churches by the Iranian Government.
More than 50 Christians have been arrested so far in the annual campaign.
In 2011, 70 Christians were arrested during this period.
Mervyn Thomas, Chief Executive of Christian Solidarity Worldwide (CSW) called for Tehran to end its harassment of religious minorities and release "all who have been imprisoned on account of their faith."