By Heba Saleh BBC correspondent in Cairo

The suicide bombings in Riyadh come at a time of mounting pressure for reform in Saudi Arabia.

Since the attacks of 11 September, in which Saudi citizens were extensively involved, the conservative kingdom has been grappling with external and internal demands for change.

In the US, politicians and commentators have accused Saudi Arabia's mixture of autocratic rule and puritanical Wahabi Islam of providing a fertile breeding ground for fanaticism and violence.

Rising violence and intolerance anger liberals and moderates

Within the country, the attacks have spurred liberals and moderate Islamists to openly express their dismay at what they consider an expanding "culture of violence" promoted by religious radicals.

Diplomats and Saudi intellectuals now say the latest atrocities are likely to inject a new urgency into the debate on reform.

Even as rescue teams were still pulling bodies out of the rubble of the devastated compounds, a leading Saudi journalist issued a strong call to action.

Jamal Khashoggi, editor-in-chief of the al-Watan daily, wrote that Saudi society had to tackle urgently what he called "an obscurantist brand of thought among us which rejects modernism, equality, tolerance and opening up to the world".

He said that those who incited violence and described its perpetrators as mujahideen were as guilty as the individuals who carried out the suicide bombings in Riyadh.

Petition

These are the first major attacks by suspected members of Osama Bin Laden's al-Qaeda inside the Saudi capital. Some in the kingdom say it has brought home the extent of the threat.

"I think this probably is going to be different. Saudis will really take a deep breath and think this is more cancerous than we thought," said a leading member of the Shura Council, the appointed body which advises the Saudi ruler.

My impression is that the attacks against the compounds may give a push for reform Western diplomat

"We have known about extremism here since the seventies," said columnist Dawood Al Shirian.

"But we have not responded to it intellectually. We just let it be and only gave importance to the security side of things. But now that there are large organised attacks, it is frightening."

More than 100 Saudi intellectuals had signed a petition earlier this year detailing a vision for political reform which includes freedom of expression and an elected Shura council.

They said they wanted to establish traditions of debate and tolerance in order to combat the culture of violence.

The country's ruler Crown Prince Abdullah invited them to a surprise meeting. He is considered by both western diplomats and Saudi intellectuals to have reformist instincts, but it's not yet clear what he has in mind.

'Wheel of change'

More than three months after the meeting, some of those involved in the reform petition say they are frustrated by the absence of any movement.

"Crown Prince Abdullah received us, and several princes have praised our project," said professor Abdullah El Hamed.

"This however, has not crystallised into a promise or even a green light for us to go ahead and spread the peaceful values of civil society."

But many caution that substantial reform is difficult for the rulers of this conservative kingdom. They say there is a fear that once the wheel of change turns, it will be impossible to stop it.

Some also say that to make significant reforms, the elderly crown prince would have to confront both a large princely class which takes its privileges for granted, and an extensive religious establishment that has been given a free hand to shape society.

"My impression is that the attacks against the compounds may give a push for reform," said a Western diplomat.

"Whether this translates into effective action we just don't know."