An Iranian pastor arrested last week has been released along with his wife, but three members of their church remain in custody, according to Christian Solidarity Worldwide (CSW).

Youcef Nadarkhani, a pastor in the Church of Iran, was arrested with his wife during a raid on their home in Rasht in the north of the country on May 13.

According to CSW's sources, they were released on the same day, but three other church members are still being detained.

Yasser Mossayebzadeh, Saheb Fadaie and Mohammadreza Omidi (Youhan) have all been previously detained by Iranian authorities. Omidi was one of four Christians sentenced to 80 lashes in 2013 for drinking alcohol during a communion service and possessing a receiver and satellite antenna.

The homes of Fadaie and Omidi were raided on May 13, and their Bibles, computers and mobile phones were reportedly confiscated.

CSW say 10 Christian homes were raided on the same day.

Pastor Nadarkhani was first arrested in 2009 after he went to his children's school to question the Muslim monopoly on Iranian education, which he considered unconstitutional.

He was charged with apostasy and sentenced to death in 2010.

Despite being asked repeatedly in court hearings to renounce his faith in order to avoid the death penalty, Nadarkhani refused.

He was released from prison on 8 September 2012, following his acquittal on apostasy charges, though he was found guilty of evangelising Muslims, for which he received three years.

He was detained again on Christmas day 2012, and released on 7 January 2013.

Iran remains one of the most dangerous places to be a Christian, ranking ninth on persecution charity Open Door's list of countries where Christians are targeted for their faith. Converting from Islam – the state religion – to Christianity is punishable by death for men, and life imprisonment for women. Last year, more than 100 Christians were arrested or imprisoned, and a number of them physically or mentally abused.

Iran has a long history of human rights abuses and violence is rapidly escalating across the country, facilitated by laws which allow the legal persecution of minority communities such as Christians and Baha'i Muslims, who have been condemned by Iranian authorities as an "illegal cult". 

"While CSW is relieved that Pastor and Mrs Nadarkhani have been freed, we remain deeply concerned for the welfare of Yasser Mossayebzadeh, Saheb Fadaie and Mohammadreza Omidi, who are still being held," said CSW's chief executive Mervyn Thomas.

"The government must be held to account for its harassment of Iran's Christian community, in particular the constant raids on homes and repeated arrests which are without basis.

"We continue to call on Iran to fully respect its constitutional and international human rights obligations by ensuring that justice and equality before the law are guaranteed to all citizens, regardless of their religion or belief."