Jeddah court also rules that some of the defendants would be banned from travel after serving their sentences
A Saudi court sentenced 33 suspected Islamist militants on Monday to up to 30 years in prison, the official Saudi Press Agency said, eight years after their arrest on terrorism charges.
Seventy-one people were arrested in Riyadh's al Nakheel district in 2006 on charges including forming a terrorist cell, possession of weapons and plotting prison escapes.
While 33 defendants were sentenced on Monday, the SPA report had no information on the status of the other 38.
The Jeddah court also ruled that some of the defendants would be banned from travel after serving their sentences.
In 2006, Saudi authorities crushed a three-year al Qaeda insurgency aimed at destabilising the U.S. ally, the world's No. 1 oil exporter. Saudi Arabia has detained more than 11,000 people in its security prisons as a result.
The remnants of that al Qaeda group fled to Yemen where in 2009 they joined local militants to form Al Qaeda in the Arabian Peninsula, now seen as one of the most dangerous branches of the movement around the world.
Saudi Arabia has put on trial hundreds of accused militants in recent months, jailing many of them and sentencing others to death on charges that they played a role in the 2003-06 insurgency or aided those going to fight in Iraq or Afghanistan.
The conservative Islamic kingdom has grown increasingly concerned about radicalisation this year because the war in Syria has spurred what they see as a surge in online militancy. Riyadh is worried about a new al Qaeda campaign of attacks.