Saudi Arabia has arrested 208 suspected militants accused of planning a series of attacks, including one targeting a state oil installation.
Interior Ministry Spokesman Gen Mansour al-Turki said the plot was against an oil facility in the east.
Gen Turki said the suspected militants had been arrested over the past few months in various parts of the country.
Saudi Arabia has been battling Islamist militants linked to al-Qaeda since a wave of bombings and shootings in 2003.
Nearly 300 security personnel, civilians and militants have been killed since then.
Gen Turki said al-Qaeda militants were still trying to gain a foothold in Saudi Arabia using the internet to recruit followers.
"There are people who believe this [al-Qaeda] ideology and they use this ideology to recruit people either inside Saudi Arabia or in any other part of the world," he told the BBC.
A cell of eight militants led by a foreigner was planning an "imminent" attack on an oil facility in an eastern province of the world's largest oil exporter, the interior ministry said in a statement.
A further 18 of those arrested were said to belong to a cell led by an "expert in launching missiles" which had infiltrated the country.
"They were planning to smuggle eight missiles into the kingdom to carry out terrorist operations," the ministry said.
Another 22 suspects were part of a group that were plotting to assassinate Saudi clerics and security personnel, the statement added.
A "media cell" of 16 people, which aimed to promote "takfiri" ideology, was arrested in Medina, according to the interior ministry.
Takfiris believe contemporary Muslim society has reverted to a state of unbelief (kufr) and thus consider legitimate both rebellion against the state and acts of violence against Muslim citizens.
In April, the Saudi authorities announced the capture of 170 suspects, some of whom they said had been training as pilots for suicide missions.