There is growing anger in the Shia community, of at least 250 million worldwide, at the intervention of troops from Saudi Arabia and United Arab Emirates in Bahrain to help repress the Shia majority which has been demanding political and civil rights.

"There is a general campaign against the Shia," said Yusuf al-Khoei of the al-Khoei Foundation, a leading Shia charitable organisation. "The best way for these [Sunni Muslim] states to gain the allegiance of the Shia is to treat them nice and stop accusing them of being Iranian spies."

Khoei said it was significant that Saudi Arabia and the United Arab Emirates were the only two Arab states to recognise the Taleban Government of Afghanistan which was notorious for persecuting Shia as heretics. He said suicide bomb attacks on Shia in Pakistan, Afghanistan and Iraq were justified according to Wahhabism, the fundamentalist version of Islam predominant in Saudi Arabia.

"The Bahraini army is wholly Sunni and the police almost entirely so, apart from some community officers," said Khoei. Shia make up 60 per cent of Bahrain's 600,000 population. Bahrain is one of only four countries in the world where there is a Shia majority, the others being Iran, Iraq and Azerbaijan. They make up only 10 per cent of Saudi Arabia's population.

The protests in Bahrain started in February as non-sectarian demands for political, civil and legal reform. But the killing of demonstrators by police has led to radicalisation, demands for an end to the monarchy, and sectarian clashes.

The al-Khalifa royal family has previously claimed reformers and protesters are agents of Iran. But, according to cables from the US embassy, it has never been able to produce evidence of this.

The Gulf monarchies' paranoia has grown since the Shia majority in Iraq took power from Saddam Hussein.