Saudi Arabia has arrested 88 suspected extremists, more than half of them ex-Qaeda detainees who had previously been released, the interior ministry announced on Tuesday.
The arrests come as part of the kingdom's drive to "punish" those "belonging to or supporting" groups classified as "terrorist," the ministry added in a statement on the official SPA news agency.
Saudi King Abdullah on Friday underscored the threat posed by jihadists unless there is "rapid" action.
The ministry said Tuesday that the suspects, arrested over past months across the kingdom, are all Saudis except for three Yemenis and one whose identity remains "unknown."
Fifty-nine of them were "previously arrested over their links to the deviant group," the name used by Saudi authorities.
The authorities launched a massive crackdown on Al-Qaeda following a spate of deadly attacks in the kingdom from 2003-2006.
It released scores of militants after passing them through a controversial rehabilitation programme set up seven years ago to persuade jihadists that their actions violate the teachings of Islam.
Signup to our newsletter and follow us on Facebook and Twitter!
But many graduates of the programme returned to militancy, including Saeed al-Shehri, who went on to become deputy leader of the deadly Al-Qaeda in the Arabian Peninsula before being killed in a US drone strike in Yemen last year.
The ministry said the latest arrests had "foiled plots they were going to start implementing inside and outside" the country.
The interior ministry in March published a list of "terror" groups, including the Muslim Brotherhood, Al-Nusra Front, which is Al-Qaeda's official Syrian affiliate, and the Islamic State, a notorious jihadist group fighting in Syria and Iraq.
It also includes the little-known Shiite militant group Saudi Hezbollah as well as Shiite Huthi rebels in neighbouring Yemen.
Saudi Arabia's top cleric last month branded Al-Qaeda and IS jihadists as "enemy number one" of Islam.
And King Abdullah was quoted as saying: "Terrorism knows no border and its danger could affect several countries outside the Middle East.
"If we ignore them, I am sure they will reach Europe in a month and America in another month."
Saudi authorities set up specialised terrorism courts in 2011 to try dozens of Saudis and foreigners accused of belonging to Al-Qaeda or involvement in the unrest unleashed in 2003.