DUBAI, United Arab Emirates (AP) — Iran has arrested about 70 Christians since Christmas in a crackdown that demonstrates the limits of religious tolerance by Islamic leaders who often boast they provide room for other faiths.

The latest raids have targeted grass-roots Christian groups Iran describes as “hard-liners” who pose a threat to the Islamic state. Authorities increasingly view them with suspicions that range from trying to convert Muslims to being possible footholds for foreign influence.

Christian activists claim their Iranian brethren are being persecuted simply for worshipping outside officially sanctioned mainstream churches.

Caught in the middle is the small community of Iranian Christians who get together for prayer and Bible readings in private residences and out of sight of authorities. They are part of a wider “house church” movement that has taken root in other places with tight controls on Christian activities such as China and Indonesia.

Iran’s constitution gives protected status to Christians, Jews and Zoroastrians, but many religious minorities sense growing pressures from the Islamic state as hard-edged forces such as the powerful Revolutionary Guard exert more influence. There are few social barriers separating Muslims and Iran’s religious minorities such as separate neighborhoods or universities. But they are effectively blocked from high government and military posts.

Iran has claimed as a point of pride that it makes space for other religions. It reserves parliament seats for Jewish and Christian lawmakers and permits churches — Roman Catholic, Armenian Orthodox and others — as well as synagogues and Zoroastrian temples that are under sporadic watch by authorities. Religious celebrations are allowed, but no political messages or overtones are tolerated.

In past years, authorities have staged arrests on Christians and other religious minorities, but the latest sweeps appears to be among the biggest and most coordinated.

In the West, the followers are drawn to house churches because of the intimate sense of religious fellowship and as an alternative to established denominations. In places such as Iran, however, there also is the effort to avoid monitoring of sanctioned churches from Islamic authorities — who have kept closer watch on religious minorities since the chaos after hard-line President Mahmoud Ahmadinejad’s disputed election in 2009.

Groups monitoring Christian affairs in the Islamic world say Iranian authorities see the unregulated Christian gatherings as both a potential breeding ground for political opposition and suspect they may try to convert Muslim in violation of Iran’s strict apostasy laws — which are common throughout the Muslim world and have at times fed extremist violence against Christians and others.

Tehran Governor Morteza Tamadon described the Christians as “hard-line” missionaries who have “inserted themselves into Islam like a parasite,” according to the official Islamic Republic News Agency. He also suggested that the Christians could have links to Britain — an accusation within Iran that refers to political opposition groups Tehran claims are backed by the West.

The crackdown by Iran resonates forcefully across the Middle East at a time when other Christian communities feel under siege following deadly attacks against churches in Egypt and Iraq — bloodshed that was noted Monday by Pope Benedict XVI in an appeal for protection of religious minorities.

The suicide blast in Egypt’s Mediterranean port of Alexandria on Jan. 1, which killed 21 Coptic Christian worshippers, followed threats by al-Qaida in Iraq over claims that Coptic leaders forced two women who converted to Islam to return to Christianity — allegations that church leaders deny.

“It’s the nature of the house churches that worries Iran. It’s all about possible converts,” said Fleur Brading, a researcher for Middle East and North Africa at Christian Solidarity Worldwide, a British-based group the follows Christian rights issues around the world. “It’s a very specific and pinpoint strike by Iran.”

Iran’s religious minorities represent about 2 percent of the population and include communities with deep connections to their faiths. Iran’s ethnic Armenian minority dates back to early Christianity, and the Jewish celebration of Purim is built around the story of the Persian-born Esther.

Even Iran’s Islamic Revolution could not stamp out the influence of the pre-Muslim Zoroastrian faith, including its new year’s holiday Norooz in March.

The wave of arrests began Christmas morning and since then, opposition websites have reported 70 Christians arrested, including those regarded as pastors in the house church movement. Many were later released, but the reports say more than a dozen remain in detention and officials have hinted more raids are possible.

It’s still unclear what charges could be brought against the jailed Christians. But allegations of trying to convert Muslims could bring a death sentence.

Brading, however, expects Iranian authorities could opt for political charges rather than religious-linked allegations to soften a possible international outcry. Iran is already struggling against a campaign opposing the death-by-stoning for an Iranian woman convicted of adultery as well as international pressure over its nuclear program.

“The use of the word missionaries instead of evangelicals is an intentional move by the government,” she said. “As evangelicals, they are a group entitled to their faith. As missionaries, they are enemies of the state seeking to corrupt its people.”

In recent months, some members of Iran’s Armenian community also have been detained on unspecified allegations of working to undermine the state, the Iranian Christian News Agency reported. Iranian officials have not given details of the reported detentions.

On Friday, a U.S. watchdog group on religious tolerance expressed concern over the recent arrests.

“What’s most troubling about this wave of detentions is the fact that Iran is continuing its recent trend of targeting evangelical Christians, which they’ve been doing for years, and also leaders from the recognized and protected Armenian Christian community,” said Leonard Leo, chairman of the U.S. Commission on International Religious Freedom, an independent government advisory panel.

Iranian authorities have come down hard on religious groups seen as threats to Islam, including the Baha’is whose faith was founded in the 19th century by a Persian nobleman considered a prophet by his followers. Baha’is are not recognized as official religious minority in Iran’s Constitution.

There are no accurate figures on the number of Christians in the “house church” movement or followers outside established denominations. But the manager of the Iranian Christian News Agency, Saman Kamvar, said authorities likely perceive some kind of challenge to the religious status quo and are “feeling insecure.”

Kamvar attributes the stepped up raids against Christians to comments last month by Iran’s Supreme Leader Ayatollah Ali Khamenei denouncing the growth of private house churches.

“This, in my opinion, was a green light to the other authorities to crack down on them,” Kamvar said from Canada, where he now lives.