In the third of a series on Middle East Shia communities, Heba Saleh reports on fears that sectarian tensions may spread to the kingdom. The US invasion of Iraq brought the country's long-oppressed Shia to political dominance, reversing hundreds of years of Sunni supremacy and emboldening the downtrodden Shia minority in neighbouring Saudi Arabia to demand equality. But now the Saudi Shia watch in dismay as the conflict in Iraq becomes increasingly sectarian. They fear that it could spill over into their country and threaten the fragile gains they have only recently started to achieve. "Until now, nothing negative has taken place," said Sheikh Hassan Al Saffar, Saudi Arabia's most senior Shia cleric. "But sometimes we hear emotional voices on both sides reacting to events in Iraq. I want to warn that if Sunnis here are encouraged to support the Sunnis in Iraq and the Shia to support the Iraqi Shia that could bring the conflict here." But he and others said the Saudi government and "wise" religious leaders from both sides were very alert to the threat to stability raised by the strife in Iraq. Part one: Shia resurgence fuels ancient fears. Roula Khalaf reports on the effect of muscle-flexing in Iran, and Iraq?s sectarian strife. One sign is that clerics from the official Sunni religious establishment have recently made repeated conciliatory statements about the importance of maintaining a dialogue with the kingdom's Shia minority. This, Shia community leaders say, is a positive development in a country where public opinion, guided by official clerics and popular preachers, has long vilified them as heretics who should be prevented from practising their rites. The Saudi Shia are estimated to number about 1.5m out of a total population of 23m, and they live mostly in the Eastern province where the kingdom's oil wealth is concentrated. They insist their loyalty is to Saudi Arabia, even if religiously they look for guidance to the ayatollahs of Iraq and Iran.
Part two: Bahrain's dawn of democracy proves false for Shia. William Wallis reports on growing disillusionment with Sunni rule. But many in Saudi Arabia, hostile to the Shia because of their religious difference, suspect them of political allegiance to Iran.
Iran's Islamic revolution in 1979 had a special resonance in the Eastern province. Broadcasts from Radio Tehran called for the toppling of the Saudi royal family. During an eruption of civil disobedience by Saudi Shia angry at discrimination, demonstrators carried the picture of Aytollah Khomeini.
This deepened the government's mistrust of the Shia and ushered in a period of increased tensions, which lasted until the early 1990s.
The Shia complain that for generations they have been subjected to officially sanctioned discrimination, prevented from building mosques, kept out of the army and the security services, and deprived of senior jobs in the bureaucracy even in areas where they form a majority.
But the rise of the Shia in Iraq, and the growing recognition within the ruling elite that Saudi religious discourse bred intolerance and contributed to the rise of al-Qaeda, dictated a change in the official attitude towards the local Shia.
Shia community leaders say the slow process of reform begun by King Abdullah, who was then crown prince, in 2003 has produced improvements. They are being allowed to build mosques and they can celebrate publicly religious festivals such as Ashoura.
For the first time, books on religious subjects by Shia authors were not banned at this year's Riyadh book fair. The mainly Shia town of Qatif now has its own local council dominated by Shia members and the local hospital has a Shia director.
No less important, according to Sheikh Hassan Al Saffar, the ministry of religious affairs has moved to curb anti-Shia rhetoric in mosques.
But hatred of Shia has been entrenched since the kingdom was established in 1932 and the government's conciliatory gestures have yet to change wider public attitudes.
Typical allegations against the Shia include the accusation that they plot against the state and that they are the enemies of the true believers, and there is religious duty to show them hostility.
A related but longer-term source of anxiety for the Shia community concerns the Saudi and other Arab Sunni militants who went to join what they consider the jihad against the US in Iraq. The inevitable return of many of them, trained and battle hardened, is a prospect that worries the Shia.
"There is certainly a sectarian aspect to the presence of those fighters in Iraq and the fear is that their return to their countries will have an impact on stability," said Jafar Al Shayeb, a Shia political activist who now heads the Qatif local council.