Updated

The Saudi government announced Monday that police arrested 16 Al Qaeda-linked terror suspects and used tractors to dig up an underground arsenal: 20 tons of bomb-making chemicals, detonators, rocket-propelled grenades and rifles.

Saudi forces also found night-vision goggles, surveillance cameras, bulletproof vests, passports and forged ID cards.

"These arrests put yet another dent in Al Qaeda (search)'s terror network," the Saudi ambassador to the United States, Prince Bandar bin Sultan, said in an embassy statement. "They should serve as a warning to anyone who would jeopardize the security of Saudi Arabia's citizens and residents that we will find them and bring them to justice."

The sweep was the latest in Saudi Arabia (search)'s high-profile crackdown on suspected terror cells, launched after the May 12 suicide bombings of Western housing compounds in Riyadh (search) killed 25 people and nine attackers.

The anti-terror raids followed repeated calls by the United States for Saudi Arabia to do more to curb Islamic militancy following the Sept. 11, 2001, attacks that were blamed on Saudi dissident Usama bin Laden's Al Qaeda group and carried out by 19 plane hijackers -- 15 of them Saudi.

"We have been making these arrests over the past four days and there are still a number of suspects we are looking for," an Interior Ministry official told The Associated Press. He said the suspects were being interrogated in connection with plotting terror attacks.

The ministry official said police also found trucks waiting to be loaded with explosives by suspects who "had been targeting vital installations to cause maximum disruption."

Saudi TV showed a truck, car and motorcycle found in the suspects' hideouts at farms and rest houses located outside the capital, Riyadh; north of the capital in the central town of Qassim (search); and at a farm in the Eastern Province.

The broadcast also showed tractors at the hideouts digging up sacks containing bomb-making chemicals and weapons that had been buried or hidden in a large cellar. The government said over 20 tons of bomb-making chemicals were found.

The arsenal included about 160 pounds of the powerful explosive RDX, 3,200 feet of fuse and more than 500 ignitors, the Saudi Embassy in Washington said. It added that there were also a number of machine guns and 18 rocket-propelled grenades with five launchers.

It was unclear if any of the 16 detainees were linked to the Riyadh bombings or a plot foiled July 15 to attack landmarks in the holy city of Mecca (search), incidents that angered many Saudis and increased pressure on authorities to do more to stamp out terrorism.

Since the May 12 bombings, police have detained at least 125 alleged militants -- many suspected of ties to bin Laden's Al Qaeda -- in almost weekly arrests publicized by Saudi authorities, apparently to offset U.S. criticism that they have been too lenient.

State Department spokesman Philip T. Reeker said he was aware of news reports about the 16 arrests but had no comment.

Saudi security forces have also killed numerous militants in fierce gunbattles. Five suspected militants with links to the Riyadh bombings died during the Mecca raid, along with two police.

A top suspect in the Riyadh suicide bombings, Turki Nasser al-Dandani, was killed this month in a gunbattle with police in northern Saudi Arabia, a week after the suspected mastermind of those attacks, Ali Abd al-Rahman al-Faqasi al-Ghamdi, surrendered to authorities.

The official told AP that such arrests are made public to reassure people that Saudi authorities are working to stamp out terrorism, in line with directives issued by the country's de facto ruler, Crown Prince Abdullah, and Interior Minister Prince Nayef.

Newspapers on Sunday quoted the crown prince as saying Saudi authorities will continue to fight terrorism aggressively until it is rooted out.

Throughout the country's major cities, security forces in bulletproof vests conduct ID checks and searches on car trunks. Cinder blocks are placed along the perimeter of all major compounds housing foreigners, side streets are blocked off, and trucks mounted with machine guns stand by entrances.