Despite a nationwide crackdown on suspected militants from the al-Qaeda terror network, and international alerts sounded by the United States, a suicide bomber drove a stolen police car into a protected compound and destroyed a good part of it, killing 11 and wounding 122.

Al-Qaeda is saying to the Saudi authorities, "We are still capable of carrying out the attacks and they begin to use anti-Saudi terminologies and I am afraid this will lead to targeting Saudis," says Jamal Khashoggi, an adviser to Prince Turki al-Faisal, the kingdom's ambassador to the United Kingdom.

"A car laden with explosives succeeded in penetrating the fortified compound surrounded by cement blocks," a security officer told AFP.

The bombing, which came a day after the United States closed its missions in the kingdom for security review, bore the marks of a carefully crafted plan, very similar to the attacks carried out on May 12, which left 35 dead.

Most of the casualties were Arabs, including four Egyptians and four Lebanese among the dead.

The London-based opposition Movement for Islamic Reform in Arabia suggested the bombers may have acted on out-of-date information.

"The mentality of mujahedeen and the literature of the al-Qaeda and related parties is very clear. There is no way they would attack Muslims unless they are collateral damage," MIRA spokesman Saad al-Faaqih told AFP.

"We are not condoning or theorising or justifying we are just describing their [mujahideen] mentality. This compound according to non-governmental sources is totally occupied by non-Muslims, mostly Americans and even the Arabs, are Arabs in origin but are Americans and Christians and may be with Arab origin."

However, residents and managers at the al-Muhaya compound said it was occupied mainly by Arabs.

The Saudi Interior ministry listed just four Americans and six Canadians among the wounded, and all were of Arab descent. Three French and one British family also lived on the compound but escaped unhurt, diplomats said.

Faqih claimed no less than 35 people were killed in the attacks, attributing his information to an informed security source. He also warned that the operation was part of a series of threatened attacks.

At the Al Hamra compound which was devastated in May, public relations manager Sheridan al-Fakhri, said security was being continuously upgraded and went to the highest state of alert after the attack on Saturday night.

"We will continue to stay on highest alert until notified otherwise," said al-Fakhri.

"Obviously you cannot stop a determined force, but we have put enough in place to have a fairly good deterrent. It's very sad that this is happening at any time but specifically during Ramadan."

Al-Fakhri acknowledged that people have left in the past three months but that most of the residents of Al Hamra, a luxurious complex, have stayed put, and learned to be vigilant.

One Westerner, an adviser to the Saudi government, said the al-Muhaya compound used to be occupied by employees of US firm Boeing.

"It's very sad. It was the old Boeing B2 compound but most of the people living there today are primarily Lebanese, Syrian and Palestinian," he added.

The militants were making a statement, "that Arabs should not try to emulate the West and live in a fenced compound with swimming pools, where men and women mingle," he said.

The challenge before Saudi Arabia, said Khashoggi is "how you could transform the mind of certain people in Saudi Arabia who are not for al-Qaeda but they share some of its narrow understandings."

Khashoggi said it was becoming more difficult for the terrorists to attack hard targets like military installations and they were instead going after soft targets.

He added that the Saudi authorities had prevented at least 10 attacks from taking place this year.

Security officials said two suspected Islamist extremists blew themselves up in Mecca on Thursday while a militant was gunned down in Riyadh in a shootout that left eight policemen lightly wounded.

Those incidents were part of a major crackdown on al-Qaeda in the kingdom where hundreds of militants have been detained and large quantities of arms seized amid repeated clashes with gunmen since May.

WAR.WIRE