The unnamed man died last week in the holy city of Medina after being detained by members of the Commission for the Promotion of Virtue and Prevention of Vice, Al-Jazirah reported.

The Arabic daily said the man "convulsed in fear after he was arrested, leading to a drop in his blood pressure and causing his death."

The man was arrested by members of the commission, commonly known as the Muttawa, for washing a car during a time of day when he should have been at prayer, the paper said.

The Muttawa enforce a strict Islamic moral code in the ultra-conservative kingdom, and are increasingly being criticised by the public for perceived abuses.

The Muttawa beat a group of Iraqi pilgrims holding British and US citizenship in the Muslim holy city of Mecca, a Saudi Shia news website said on August 6.

The Shia news website rasid.net said the Muttawa beat the pilgrims with sticks after accusing them of being "infidels" as they circled the holy Kaaba stone at the Grand Mosque, Islam's holiest site.

The head of the Muttawa, Ibrahim al-Ghaith, said the Bangladeshi man "fainted" while being transported in a vehicle and that doctors found no signs of "assault or torture" on his body, Al-Watan newspaper reported.

Three commission members and policeman who witnessed the incident were questioned before being completely exonerated, it added.

Complaints about excesses attributed to the 5,000-strong force have become increasingly common in the local press in recent months.

The English-language daily Arab News reported last week that a Nigerian convert to Islam was jailed in Riyadh after he helped a sick 63-year-old woman and was then accused by the religious police of immoral behaviour.

Earlier this month, a court acquitted three members of the Muttawa and a policeman over the death of a man in their custody in the northwestern city of Tabuk. He too had been accused of associating with a woman who was not a relative.

The interior ministry issued a decree in May 2006 that aimed to rein in the Muttawa by requiring them not to interrogate detained suspects, as they had previously done, but to hand them over to the regular police instead.

However, Interior Minister Prince Nayef bin Abdul Aziz last month defended the Muttawa, accusing journalists of exaggerating recent abuse allegations.