Bahais, whose headquarters are in Haifa, are seen as heretics in Iran

They were convicted for propaganda against the system in the southern city of Shiraz, a judiciary spokesman said, without giving details.

The Bahai faith is viewed as heresy by Iran's religious authorities.

The spokesman said the 51 suspended sentences were conditional on attending courses by state propaganda officials.

The defendants were arrested early last year, according to officials.

The authorities said they were proselytising in the southern city of Shiraz under the cover of helping the poor.

Speaking at his regular news conference, spokesman Ali Reza Jamshidi said the 51 had already been freed.

Iran's constitution recognises only Islam, Christianity, Judaism and Zoroastrianism as legitimate religions.

Corrupt official hanged

At the same briefing, Mr Jamshidi announced that a customs broker had been executed for corruption and bribery.

Three other customs officials were condemned to death in the same case - involving a bribe of 10bn rials ($1m or £0.5m) - but they had appealed for their sentences to be reduced to life imprisonment.

Mr Jamshidi admitted it was "rare" for the death sentence in Iran to be handed down for financial crimes and may have been the first such case.

Iran is one of the world's heaviest users of the death penalty, most frequently for violent crime and sex offences.

Media reports put the number of convicts executed this month at 28. About 300 were executed last year.