Riyadh launches full-scale anti-terrorism sweep as rulers acquiesce to American demands to interrogate long list of potential suspects

Saudi Arabian authorities have embarked on a vast anti-terrorism operation in which up to 12,000 citizens will be questioned at the behest of the US, a Saudi opposition group has told the Guardian.

"The Saudi government is doing a full-scale sweeping activity," said Saad al-Fagih, of the London-based Movement for Islamic Reform in Arabia.

"This is causing occasional confrontations with members [of militant groups] who have taken a decision not to surrender themselves."

Several sources in the kingdom had told him of a "substantial list", provided by the US, naming Saudi citizens to be questioned or arrested, he said.

One source put the number of names at 12,000. Others gave lower figures but all were well into the thousands. "There are strong signs that the number is 12,000," Mr Fagih said.

The information had been compiled by the US from various countries, including Pakistan, Bosnia, and Russia.

Some names were included as they had been mentioned by suspects under interrogation but others were on the list because of money transfers or travel bookings.

"It doesn´t mean they are all suspects or wanted, but they all have to be interviewed."

Saudi Arabia is reluctant to admit cooperating with the US for fear of inflaming domestic opinion, but it also needs to placate American critics who say it has done too little to combat terrorism.

The result of that, say security analysts, is that Riyadh and Washington collaborate in private far more extensively than either side will admit.

There is also no doubt that Saudi Arabia is in the midst of an unprecedented security trawl. In recent weeks at least 15 anti- terrorism raids have been reported in the kingdom - though others have almost certainly gone unreported.

On Wednesday, Britain and the US issued new warnings for travellers to the kingdom. The state department advised American citizens "to defer non-essential travel".

It said: "The US government has received indications of terrorist threats aimed at American and western interests, including the targeting of transportation and civil aviation. There is credible information that terrorists have targeted western aviation interests in Saudi Arabia."

In London, the foreign office, which also advises against non- essential travel, said: "There is information of a threat to British aviation interests in Saudi Arabia."

A few hours earlier British Airways suspended all flights to the kingdom after Saudi authorities uncovered an apparent plot to shoot down a BA plane near Riyadh.

Crown Prince Abdullah, Saudi Arabia´s de facto ruler, told security officials yesterday that the kingdom was engaged in a "decisive battle" against terrorism. "In the struggle between forces of good and forces of evil, there is no room for being neutral or hesitant," he said in a speech reported by the official Saudi news agency.

His remarks reflected the government´s changed attitude towards internal terrorism which, before the suicide bombings on May 12 that killed 35 people including nine attackers in Riyadh, usually amounted to denying there was a serious problem.

The claim that Saudi authorities were working through a US-supplied list of suspects could not be independently confirmed yesterday, though the US is known to have supplied a shorter list to Yemen.

The kingdom has publicly turned down requests to let the FBI question suspects, so accepting an American list of people to be interviewed by Saudi officials could be a compromise solution.

Last month, police found underground arsenals at farms in the kingdom, and vehicles ready for use as bombs. They also found fake passports, spying equipment and donation boxes.

"The extremists had infiltrated and developed sleeper cells in Saudi Arabia to an extent that neither society nor the authorities were aware of," Mishari al-Thaidi, a journalist and expert on militants, told the Associated Press.

"I believe they were still in the process of getting organised and setting themselves up when they were raided."

· A Moroccan student went on trial in Germany yesterday, accused on more than 3,000 counts of being an accessory to murder for providing logistical support to the September 11 terrorist attackers in the US, writes Ben Aris in Berlin.

Abdelghani Mzoudi, 30, an electrical engineering student in Hamburg, is also charged with being a member of a terrorist group. He denies the charges. (Guardian Unlimited © Guardian Newspapers Limited 2003 08/15/03)