Iran has arrested more than 100 Christians in the last week, charities report, amid a growing crackdown by the Islamic Republic.

Many of the 114 detained were converts to Christianity from a Muslim background, accused of “proselytising”.

They had to report the history of their Christian activities and were told to cut contact with any Christian groups, according to Open Doors UK, a charity which speaks out on persecution against Christians.

While Christianity has existed in Persia since Christ’s death, many believers fled after the Shah was deposed in a coup and Ayatollah Ruhollah Khomeini was installed in the Islamic revolution of 1979.

There are no official records, but there are estimated to be some 350,000 remaining in Iran - some one per cent of Iran’s population, with a rising trend toward converting to Christianity.

Christian advocacy groups report a growing underground evangelical movement in Iran, where they say increasing numbers of people who have become curious about the minority religion.