A church in the Iranian capital of Tehran has reportedly been forced to close by the intelligence branch of the Iranian Revolutionary Guard.

Local sources report that the pastor of the Assemblies of God-affiliated church was ordered to cancel all church activities and seal up the property.

Christian Solidarity Worldwide (CSW) said that there would be no services at the church, situated in the Janat-Abad area, until the order was reversed.

The human rights organisation said that the Revolutionary Guard was known for using aggressive methods and was usually deployed in situations deemed to threaten national security or stability.

Sources have told CSW that all Farsi-speaking churches in Tehran are being threatened with closure.

One source close to CSW said: “If this aggressive campaign to eliminate evangelical Christianity is not stopped, it is a matter of time before all Farsi-speaking churches are forced to shut down."

Government-sanctioned churches have been the target of a crackdown by the authorities since the end of 2011, CSW says.

Just before Christmas, an Assemblies of God church in Ahwaz was raided and the congregation, including children, were detained.

This year, the leaders of the Anglican churches of St Paul's and St Peter's in Esfahan were detained. The head of St Paul's was temporarily released on bail in May.

Last month, the leaders of the AOG Central Church in Tehran revealed that the Iranian Intelligence Ministry was demanding intrusive information on members of the congregation, including identity card numbers.

More recently, members of Emmanuel Presbyterian Church in Tehran were detained, and the church was ordered to cease all weekly activities with the exception of its Sunday services.

Iran has also seen an upsurge in the harassment, arrests, trials and imprisonments of converts to Christianity since the beginning of 2012, particularly in Tehran, Kermanshah, Esfahan and Shiraz.

CSW’s Advocacy Director, Andrew Johnston, said that churches in Iran were facing increasing harassment and that the closure of the church in west Tehran "marks a particular escalation".

"This not only underlines Iran’s continuing campaign to depict legitimate Christian activity as a danger to the state, but also sets a dangerous precedent by providing a blueprint for further church closures by the regime," he said.

"CSW is calling for the immediate re-opening of this church and urges Iran, as a signatory to the Universal Declaration of Human Rights and the International Covenants on Human Rights, to fulfill its obligations and ensure religious freedom in its fullest sense for Christians and other religious minorities in the country.”