Princes, ministers and a billionaire business tycoon were among dozens of high-profile figures arrested or sacked at the weekend, as Crown Prince Mohammed bin Salman consolidates power.
The purge comes amid heightened regional tensions, with Saudi Arabia and Iran facing off over a missile attack from Yemen and a political crisis in Lebanon after prime minister Saad Hariri's shock resignation announced from Riyadh.
"A total of 208 individuals have been called in for questioning so far... Seven have been released without charge," the Saudi information ministry said in a statement, quoting attorney general Sheikh Saud al-Mojeb.
Authorities have frozen the bank accounts of the accused and warned that assets related to the alleged corruption cases would be seized as state property, as the government appears set to widen the crackdown.
"The potential scale of corrupt practices which have been uncovered is very large," the statement said.
"Based on our investigations over the past three years, we estimate that at least USD $100 billion has been misused through systematic corruption and embezzlement over several decades."
High-profile figures, including billionaire tycoon Prince Al-Waleed bin Talal, were arrested or sacked in the crackdown -- just after an anti-graft commission headed by the crown prince was established.
- Rising tensions -
Prince Mohammed, the son of 81-year-old King Salman, is already seen as the country's de facto ruler controlling all the major levers of government.
The crackdown comes as he moves to accelerate his Vision 2030 programme to modernise the conservative kingdom, but also as Riyadh takes a more aggressive stance in its wider region.
In the wake of a failed missile attack against Riyadh airport on Saturday, which was claimed by Iran-backed Huthi rebels in Yemen, the kingdom has accused Tehran of "direct aggression".
Iran vehemently dismissed the charge that it supplied missiles to the Huthis and warned Saudi Arabia of its "might", prompting fresh acrimony between the regional heavyweights.
The tensions appear to be playing out in Beirut, the latest front line of the power struggle between Saudi Arabia and Iran.
On Saturday, Hariri cited Iran's "grip" on Lebanon and threats to his life when he announced his resignation in a televised speech from Riyadh, precipitating a new political crisis in Beirut.
Saudi Arabia on Thursday urged its citizens to leave Lebanon "as soon as possible" and also called on them not to travel to the country, without specifying any threat.
Lebanese Foreign Minister Gebran Bassil on Thursday demanded the return of Hariri from Saudi Arabia, amid media reports that he was being held in the kingdom.
The regional tensions could escalate the proxy conflict between Riyadh and Tehran, which back opposing sides in wars and power struggles from Yemen to Syria.