Religious freedom advocacy Christian Solidarity Worldwide has called for the convictions of three Iranian Christians to be overturned after they were found guilty of national security-related crimes last month.

Mervyn Thomas, CEO of the UK-based organisation, said the eight year sentences handed down to Suroush Saraie and Eskandar Rezaie - both members of the Church of Iran - and the one year sentence handed down to Zahra Norouzi Kashkouli were "yet another example of the unjust treatment of Iranian Christians, who are being criminalised on account of their faith".

"We call for these convictions to be overturned, and for the Iranian government to end its harassment of religious minorities. We urge the EU, the UK and the US to ensure that improvements in freedom of religion or belief and other human rights are a central part of any dialogues with the Iranian government.”

CSW reports that Mr Saraie and Mr Rezaie each received seven year sentences for "creating a group that works against national security", and an additional year for "propaganda against the state" in a verdict handed down on 28th December. Ms Kashkouli was sentenced to a year in prison for "being a member of a group working against the system" in the same hearing. All three are appealing their sentences.

Both Mr Saraie and Mr Rezaie have already served prison sentences after they were arrested in 2012 during a prayer meeting. They were released from prison in November, 2015, but both rearrested in July last year, spending a few months in prison before being released on bail.

It is not yet clear whether they will be able to remain on bail while their appeals are heard.

CSW says that despite a statement in the Iranian constitution forbidding the investigation of individuals’ beliefs and adding that "no one may be molested or taken to task simply for holding a certain belief", there has been a rise in arrests of members of minority faith communities since the advent of the Rouhani presidency, and Christians have routinely been charged with national security-related crimes in order to justify excessive sentences.

News of the verdicts comes as pressure grows on Iran's Islamic leadership. Recent anti-government rallies, which broke out in late December, have left more than 20 people dead.