A top Saudi security official said Tuesday that police had arrested 88 men suspected of being part of an Al Qaeda cell that was plotting attacks inside and outside of the kingdom.

Interior Ministry spokesman Mansour al-Turki did not give any details about the alleged plots, but said 59 of men arrested had previously served prison sentences for similar offenses.

Al-Turki said that Saudi security forces monitored the group for months and learned about their plans. He said the arrests were made over the past several days and that Saudi forces "are serious in tracking down" anyone who joins a terrorist group.

"It is unfortunate that some of those who had completed their sentences and were released by court orders returned to their previous ways," al-Turki told reporters.

The police said that three of the men are Yemeni nationals, one is still being identified and the rest are Saudis.

The announcement comes amid the advance of the Islamic State extremist group in Iraq and Syria, which has prompted Saudi Arabia to take harsher measures against sympathizers who could threaten the kingdom's stability. The kingdom made it illegal this year for its citizens to fight as militants abroad and for anyone to incite youth to fight in foreign countries.

Over the weekend, Saudi King Abdullah warned that extremists could attack Europe and the U.S. if there is not a strong international response to terrorism. His remarks were believed to be in reference to the Islamic State group's offensive.

Saudi security officials began battling Al Qaeda militants around a decade ago when extremists launched a string of attacks in the kingdom aimed at toppling the monarchy. Saudi officials responded with a massive crackdown that saw many flee to neighboring Yemen. In the time since, the kingdom has not seen any massive attacks, though it has imprisoned suspected militants and sentenced others to death.

On Monday, a court in the capital, Riyadh, ordered 17 people to serve sentences ranging from just under three years to 26 years in prison. The group was allegedly part of a 67-member cell whose members either fought in Iraq, facilitated travel for militants to fight there or helped finance terrorism. All have 30 days to appeal their sentences.

Also on Monday, the same court sentenced a Saudi preacher to five years in prison for allegedly praising and supporting the Islamic State group and Al Qaeda during a recent sermon. The Saudi-run Arab News reported that the preacher also called for attacks on Egypt's security forces and on Saudis to release a female Al Qaeda operative.

The defendant was banned from delivering sermons and from traveling abroad for five years after his release from prison. His lawyers plan to appeal.