Iran is a majority Muslim country, on in which Islam is enshrined in the constitution and all laws are subject to Islamic principles. Indeed, the country's official title is the Islamic Republic of Iran.

You'd think, therefore, that Iran would be a safe haven for Muslims; a nation where there are none of the anti-Muslim persecutions that happen in other parts of the world.

But you'd be wrong.

In recent months, there has been a wave of arrests of Sunni Muslims. Dozens are currently on death row and at risk of death by the sadistic Iranian method of hoisting on cranes and slow strangulation by hanging. How can this be?

Iran is a Shia Muslim state. Muslims who don't adhere to the Shia interpretation of Islam are regarded with official distrust and disrespect. They often suffer discrimination - and sometimes much worse.

While Iran officially claims to defend the rights of Islamic minorities - their freedom of faith is enshrined in the constitution - the reality is very different. Followers of non-Shia Islamic sects are deemed not true Muslims. They are seen as potential enemies of the state and of God, which is a capital office. This is particularly the case with Sunni Muslims. The Shia-dominated Tehran regime regards them as their main religious rivals - and a threat.

In everyday life, Sunni Islam is tolerated up to a point. But whenever it gains converts or influence, the state cracks down - particularly in the ethnic minority Kurdish, Arab and Baluch regions of Iran.

Last November, two Sunni prisoners of conscience from Iran's Baluch minority were executed. According to the Human Rights Activists News Agency (HRANA), 22-year old Vahid Shah Bakhsh and 23-year old Mahmoud Shah Bakhsh were hanged on charges of 'Moharabeh [enmity against God] and acting against national security'.

Both men had been subjected to severe torture at the Ministry of Intelligence Detention Centre in Zahedan. There are serious doubts about the evidence against them and the fairness of their trial. That same month the Supreme Court of Iran confirmed the 33-year jail term imposed on an Iraqi Sunni Muslim, Marivan Abdolkarim Reza, who was found guilty on similarly vague charges.

Also last November, 16 Sunni converts from Iran's Ahwazi Arab minority were arrested during a Qur'an class in Ahwaz city, according to HRANA.

Meanwhile, the International Campaign for Sunni Prisoners in Iran (ICSPI) reports: "The pro-Shia Iranian government has been alarmed by the rise of Sunni Islam among the Ahwazi Arabs in the traditionally Shia-majority Khuzestan province.

"At least 10 Sunni converts were arrested in July 2014, with three arrested after preaching Sunni beliefs and seven arrested after holding congregational Sunni Taraweeh prayers during Ramadan."

More than 20 Sunni converts were arrested last February at a Qur'an and Arabic language study meeting in Koye Alawi in Ahwaz city. The ICSPI adds that, "only a month ago, a further two Muslims from Iran's Ahwazi Arab minority, who had preached Sunni beliefs after converting from Shi'ism, were charged with 'causing corruption on earth', a charge which carries the death penalty.

"The Iranian authorities claim the two Sunni preachers, Hossein Saboori and Sami Zebady Alboghobesh, were involved in burning down a Husseiniya [a Shia place of worship]. The two men have strongly denied the accusation.

"The Iranian authorities often falsely accuse Sunni preachers and activists of involvement in various incidents in an attempt to justify their arrest. In some cases, a single incident has been used as justification for the imprisonment of dozens of different Sunni activists."

Intensification of persecution

The Iranian human rights organisation, the Abdorrahman Boroumand Foundation (ABF), confirms that the repression of Sunni Muslims has been intensifying since late 2012 when six young Kurdish Sunni activists were hanged in Rajai Shahr Prison. Their execution was shrouded in secrecy, as was the judicial process that stripped them of their rights to due process and a fair trial.

The six activists were tried along with four other young Sunnis - Shahram Ahmadi, Jamshid and Jahangir Dehqani and Kamal Mola'i - who are also now at imminent risk of execution. All 10 defendants said their confessions were extracted from them after months of torture and solitary confinement and after promises of leniency.

ABF observes: "Sunni Muslims are estimated to constitute about 10% of Iran's total population. According to Article 12 of the Islamic Republic's Constitution, they can practice their faith freely. In practice, however, the Shia rulers of Iran have subjected Sunnis to discrimination and have denied them political, civil, economic, social, and cultural rights, through restrictions in access to government positions, employment, education, and places of worship.

"Sunnis live in a majority in the most impoverished provinces of Iran, such as Kurdistan, Turkmen Sahra, and Sistan & Baluchestan, and the uneven distribution of resources remains one of their main grievances, vis-a-vis the central government."

Blocking entry into mosques

Restrictions on places of worship for Sunnis are cited by Human Rights Watch, including the refusal of permission to build new mosques and blocking entry into mosques on important Sunni religious occasions. A 2008 report by Amnesty International noted that there was not a single Sunni mosque in Tehran.

"The religious institutions of Sunni Kurds are generally blocked, while those of Shias are encouraged and supported by the state...the government has restricted the expansion of Sunni mosques that exist elsewhere in the country," said Amnesty.

The Iranian government's objective seems to be to restrict the growth and influence of Sunni Islam and to encourage Sunnis to pray in mosques controlled by Shia clerics in the hope of eventually converting them. With this in mind, dissident Sunni clergy have been detained, imprisoned, exiled and even executed for the vaguely worded offence of "waging war against God."

In 2014, a report by the UN Special Rapporteur on Iran stated that at least 150 Sunni Muslims are currently "detained for reportedly organising religious meetings and activities or after trials that allegedly often failed to meet international standards."

These failures include being denied access to their lawyer and the right to call evidence and witnesses in their defence; as well as subjecting the accused to 10-minute summary trials while shackled and blindfolded.

Many Sunnis believe their persecution is aimed at stopping them from promoting their own interpretation of Islam, raising awareness about the unjust treatment of Sunnis and exposing the misuse of religion by the state.

For more information about Peter Tatchell's human rights campaigns, to receive his email bulletins or to make a donation: www.PeterTatchellFoundation.org.

For more on the International Campaign for Sunni Prisoners in Iran, go to their website here.