A group of Christians imprisoned after a raid on a prayer meeting in Iran have lost appeals against their sentences.

The sentences being served by the six Christians vary in length and were upheld by a court on 29 March following an appeal.

The group, from Shiraz, were arrested on 12 October 2012 and the following July were charged with 'action against the national security' and 'propaganda against the order of the system'.

Mohammad Roghangir was sentenced to six years in prison, Massoud Rezai to five years.  Mehdi Ameruni and Bijan Farokhpour Haghighi received three year sentences, Suroush Saraie two and half years, and Eskandar Rezai was given a one-year sentence.

They were arrested and detained alongside two others who have since been freed. The court decided to drop charges against Roxana Forghi, who had received a one-year sentence. Shahin Lahouti, who also received a two and a half year sentence, was released from prison in December last year.

Mervyn Thomas, chief executive of Christian Solidarity Worldwide, said he was disappointed that the change of president had not halted the detention of religious minorities in Iran, despite promises of equality for all citizens.

He said religious minorities in Iran, including the group from Shiraz, were being detained on false political charges.

"We call for the charges against the six Christians sentenced to be dropped, urge the government to end the practice of characterising legitimate religious activities as national security crimes, and to uphold the right of all religious minorities to freedom of religion and belief, as contained in Article 18 of International Covenant on Civil and Political Rights (ICCPR), which includes to right to change one's belief, and to which Iran is signatory," he said.

CSW is also calling for the release of Vahid Hakkani, a convert to Christianity, who according to Mohabat News has been on hunger strike since 20 March after losing his appeal for conditional release.

He was sentenced last June alongside three other converts by Branch 3 of the Revolutionary Cour, receiving three years and eight months in prison.

The charges against him were of 'attending house church services', 'promoting Christianity', 'propagating against the regime' and 'disturbing national security'.

He has taken the drastic measure of going on hunger strike despite suffering from digestive problems, which needed surgery late last year. Christian Solidarity Worldwide (CSW) understands that his health is deteriorating rapidly.

Mr Thomas appealed to Iran to grant his unconditional release.

"We call on the Iranian authorities to bring an end the harassment of religious minorities and to ensure that every Iranian citizen is able to enjoy the rights and freedoms to which they are entitled under national and international law, including the right to freedom of religion or belief," he said.