Iran has arrested a number of Christian missionaries in Tehran province and vowed to detain more of them, the provincial governor was quoted as saying by state news agency IRNA on Tuesday.
Morteza Tamaddon said "the leaders of this movement have been arrested in Tehran province and more will be arrested in the near future."
He did not give their identities, so it was unclear whether they are foreigners, Iranians or a combination of both.
Nor did he explain what he meant by their belonging to a movement, which he called "deviated" and "corrupt."
He referred to them as "tabshiri," or missionaries, and likened them to the Taliban.
"Just like the Taliban... who have inserted themselves into Islam like a parasite, they have crafted a movement with Britain's backing in the name of Christianity," Tamaddon said.
"But their conspiracy was unveiled quickly and the first blows were delivered to them," he added, without saying what they were allegedly conspiring to do.
"Various kinds of fake, deviated and corrupt cults have sharpened their teeth for our beliefs and one can see their activities among the youth," he said, branding Christian missionaries as an example of "cultural onslaught" against Iran.
Christianity is among the recognized religions in Iran but, under the country's Sharia-based law, renouncing Islam, or apostasy, is punishable by death.
However, some Christian converts have been jailed in recent years and media have reported several crackdowns on "home churches" in predominantly Shiite Muslim Iran.
Christians, Jews and Zoroastrian minorities are free to practice their religion but they are not allowed to proselytize, and their women have to observe the mandatory Islamic dress code in public.