The arrest of 172 suspected militants did not end the al Qaeda-linked threat in Saudi Arabia, the interior minister was quoted on Saturday as saying.
Prince Nayef told the Arabic-language al-Riyadh daily a Saudi man was held on suspicion of being the spiritual leader of the largest of the seven cells which were smashed, foiling a plot to attack oil facilities and military bases.
"We cannot say that we are finished from these deviants," Prince Nayef said. "But efforts will continue. The eyes...are wide open and efforts are under way to purify our country from every evil."
The Interior Ministry said on Friday it had foiled an al Qaeda-linked plot to attack oil facilities, military bases and public figures, arresting 172 people, including some who it said had trained to use aircraft for suicide attacks.
Most of those arrested were Saudis, and security sources said others were from Yemen, Nigeria and other countries. Police seized weapons, computers and more than 20 million riyals ($5 million) in cash.
Islamist militants swearing allegiance to al Qaeda launched a violent campaign to topple the US-allied Saudi monarchy in 2003, carrying out suicide bomb attacks on foreigners and government installations, including the oil industry.
Saudi Arabia is the world's top oil exporter, supplying about 7 million barrels a day to world markets. It holds nearly a quarter of the world's oil reserves. Thomas Hegghammer, a Norway-based counter-terrorism expert, said the men were arrested over a period of nine months.
"I don't see it as one big plot... These guys were picked up over a period of nine months, and I suspect they include many different groups involved in a variety of activities," he said. Such activities might include recruiting militants for Iraq and Internet propaganda, he said.
The last announced break-up of a major cell was in December. "We're seeing a new communication strategy from the Interior Ministry. Instead of announcing arrests as they happen - which projects an image of continuous instability - they save them up and present them in bulk," Hegghammer said.