Christian Solidarity Worldwide has condemned as “brutal” the arrest and detention of 70 Christians during the Christmas period in Iran.

Twenty-five of them were rounded up in the early hours of Christmas Day. CSW said another 50 Christians were detained although their circumstances remain unclear.

The 25 detained on Christmas Day were evangelicals and included pastors and leaders from Iran’s house church networks, which are under severe pressure from the government.

Eleven of the group have so far been released but CSW said it had “serious concerns” for the 14 who remain in detention.

Andrew Johnston, Advocacy Director of CSW, said: “We condemn this brutal attack on evangelical Christians in Iran.

“The arrest of 70 members of one group reveals the clear targeting of individuals along religious lines.

“Iran is a signatory to the International Covenant on Civil and Political Rights and is therefore legally obligated to uphold international standards of religious freedom for all its citizens.”

CSW said members of house churches have been subjected to brutal interrogations and solitary confinement at the hands of the authorities looking to extract the names of other church members and deter them practising their faith.

It said it was troubled by the anti-Christian rhetoric of religious and political leaders in the media.

Most recently the Governor of Tehran, Morteza Tamadon, described Christians as ‘tabshiri’, or ‘missionaries’, and threatened more arrests during a speech in Tehran on Tuesday announcing the arrest of several evangelical leaders.

He told the state-run IRNA news agency: “Just like the Taliban … who have inserted themselves into Islam like a parasite, they have crafted a movement with Britain’s backing in the name of Christianity.”