New York, USA - Members of the Baha'i community in Iran are the most persecuted religious minority in the Islamic Republic, where suppression of alternative faiths is growing worse, U.N. special rapporteur for human rights in Iran Ahmed Shaheed said on Monday.

Shaheed also warned that the increasingly harsh sanctions against Tehran over its nuclear program may be preventing normal Iranians from exercising their human rights because they face greater difficulties accessing medicine and other basic necessities.

"By and large I would say the Baha'is are the most persecuted religious minority in Iran," he told a seminar at the International Peace Institute in New York.

The Baha'i faith is not a recognized religion in Iran, which Shaheed said was likely the main reason its practitioners were being persecuted.

"The numbers of Baha'is that are in prison have increased, over a hundred at the present time according to the information I have," Shaheed said.

"They face a whole range of discrimination, from being unable to practice their faith, being denied access to basic services," he said. "And often they face charges unrelated to their faith, national security charges."

Baha'is regard their faith's 19th-century founder as the latest in a line of prophets including Abraham, Moses, Buddha, Jesus and Mohammad. Iran's Shi'ite religious establishment condemns the faith as heretical.

Shaheed will present his annual report on rights in Iran to the U.N. General Assembly's human rights committee later this week. His report details how rights activists in Iran face beatings with batons, mock hangings, rape and threats that family members will be raped or killed.

'HARASSMENT CONTINUES'

He told the audience of diplomats, U.N. officials, rights advocates and journalists that other religious minorities also faced persecution in Iran, an allegation Iran's government has denied.

He said that even officially tolerated religious minorities, such as Sunni Muslims, Dervishes and Christians, faced persecution and discrimination.

"The broad picture is the harassment continues, and the same goes for other minority religions which are ... recognized in the constitution," said Shaheed, a former foreign minister of Maldives.

Last month Shaheed said that more than 300 Christians have been arrested since mid-2010. He expanded on those concerns on Monday during his presentation in New York.

"Targeting of new converts is what's really at issue at the present time, those who convert from, say, Islam to Christianity are targeted for persecution and those who proselytize or evangelize are targeted for persecution," he said.

He also echoed concerns raised by U.N. Secretary-General Ban Ki-moon, who said in a report published last week that international sanctions on Iran were having "significant" effects on the Iranian people and also appeared to be harming humanitarian operations.

Shaheed said there were increasing reports of "shortages that can have an impact on the ability of people to realize their basic human rights, for example in medicines and so on."

So far Iran has not allowed him to visit the country to carry out his work, though Shaheed said he was urging Tehran to allow him to visit and assess the impact of sanctions, as well as the general human rights situation.

"What I am saying is that I am not able to speak on the subject authoritatively without investigating further," he said.

Iran has been hit by U.N., U.S., European Union and other Western sanctions for refusing to halt a nuclear program Tehran says is entirely peaceful but which Washington and its allies say is aimed at amassing the capability to produce atomic bombs.