Pastor Behrouz Sadegh-Khandjani, Mehdi Furutan, Mohammad Beliad, Parviz Khalaj and Nazly Beliad were last year sentenced to one year in jail for crimes against the Islamic Order.

They were recently released on bail after serving eight months of their sentence and are appealing the judgement.

At the time of their arrest, the Christians were also charged with blasphemy, apostasy and holding political meetings.

After being jailed for crimes against the Islamic Order, the group had presumed that the other charges had been dropped. It emerged last month, however, that they were to stand trial for blasphemy at a lower court.

Christian Solidarity Worldwide reports that the trial has been adjourned until April 12 to give the prosecution more time to gather evidence.

Lawyers representing the men maintain that there are no legal grounds for the blasphemy charges and are optimistic that the case will eventually be dismissed, CSW said.

CSW National Director, Stuart Windsor, urged the Iranian government to ensure that the men receive due process and are acquitted of all charges that "have no legal bearing under Iranian law".

He expressed concern for Pastor Yousef Nadarkhani, who is in prison awaiting an appeal against his death sentence for apostasy, and criticised the reinstatement of a 20-year prison sentence for seven Baha'i leaders detained without trial since 2008.

"The international community must press Iran to end the arbitrary arrest and imprisonment of religious minorities purely on account of their faith," he said.