Britain and Germany joined the United States in closing their diplomatic missions in Saudi Arabia (search) after officials warned Al Qaeda (search) was plotting new attacks and U.S. officials raised the national terror alert level.
As embassies and consulates shut down, Saudi security officials said Tuesday three suspected Al Qaeda militants had been arrested in the southwestern port of Jiddah. The arrests on Monday followed the homicide bombings of three residential compounds on the outskirts of Riyadh on May 12.
No details of the arrests were released, and it was unclear whether investigators believe the three men were connected to the bombings. Authorities have linked the attacks to Saudi-born dissident Usama bin Laden's Al Qaeda terror network.
Four other suspects apparently linked to Al Qaeda were in custody for the Riyadh car bombings, which killed 34 people, including eight Americans, two Britons and nine attackers. Nearly 200 people were wounded.
Later Tuesday, John Burgess, a political officer at the U.S. Embassy in Riyadh, said Saudi officials had arrested two Moroccans on suspicion of being involved in the attacks and were seeking a third Moroccan. It was not clear if the Moroccans were among the three arrests on Monday.
On Friday, homicide attackers killed 29 people in Casablanca (search), Morocco, in nearly simultaneous assaults. Investigators said they suspected the attacks were the work of homegrown Islamic extremist groups because of apparent miscalculations that indicated the attackers lacked the sophistication of bin Laden's well-trained operatives.
In Washington, the government raised the national terrorism alert to orange, signifying a "high" risk of attacks, from yellow, meaning an "elevated" risk. The change came after a review of intelligence information by President Bush's homeland security council Tuesday, White House spokesman Ari Fleischer said. Orange is the second-highest on the five-color alert scale.
"The U.S. intelligence community believes that Al Qaeda has entered an operational period worldwide, and this may include attacks in the United States," Homeland Security Secretary Tom Ridge said.
The U.S. Embassy in Riyadh said it will close its mission in the Saudi capital as well as the consulates in Jiddah, about 190 miles southwest of Riyadh, and Dhahran, 300 miles east of Riyadh, on Wednesday. It hopes to reopen them on Sunday.
"The Embassy continues to receive credible information that further terrorist attacks are being planned against unspecified targets in Saudi Arabia," Americans were warned in a statement posted on U.S. Embassy and consulate Web sites.
Citing an imminent threat of attacks, the British Foreign Office in London announced its embassy in Riyadh, the consulate in Jiddah and a trade office near Dhahran would close over the same period.
The German Foreign Ministry said in Berlin that it was shutting the consular section of its embassy in Riyadh and another mission in Jiddah until the end of the week. No other details were given.
A Saudi official said on condition of anonymity Tuesday that investigators were aware of about 50 militants, some now dead, believed to belong to three Saudi cells, including the one that carried out the May 12 bombings. Another cell has fled Saudi Arabia and the third is at large in the kingdom, the official said.
The official indicated the surviving militants were ready to volunteer for more homicide strikes, were tied to Al Qaeda and had hardcore sympathizers numbering "in the low hundreds."
The Riyadh attacks have been seen as not only an attack on U.S. and other Western interests, but also a strike on the Saudi government for its close ties with America and its decision following the 1991 Gulf War to allow American troops to be stationed in Saudi Arabia.
Bin Laden said the U.S. presence defiles the country, which is custodian of Islam's two holiest shrines.
The United States announced last month that its air operations base would move from Saudi Arabia to Qatar.
Crown Prince Abdullah held a palace reception Tuesday for the families of those killed and wounded in the bombings. He told the families the "apostates" responsible for the attacks would be caught and punished.
More than 60 FBI and other U.S. investigators are assisting Saudi authorities with the probe into the attacks.
Interior Minister Prince Nayef has said four suspects in custody for the Riyadh car bombings are apparently linked to Al Qaeda.
Nayef said investigators had identified three of the badly mangled bodies of nine Saudi men thought to have carried out the Riyadh attacks. The three were among 19 suspects sought in connection with a weapons cache found May 6 linked to Al Qaeda.
The government had said the 19 were believed to be receiving orders directly from bin Laden and had been planning to use the seized weapons to attack the Saudi royal family and American and British interests.