The crackdown was spearheaded by Crown Prince Mohammed bin Salman, 32, and led to the arrest of at least 11 other princes, including billionaire tycoon Alwaleed bin Talal, a cousin 30 years his senior. The arrests were intended to send a potent message that the self-dealing that had become endemic in the kingdom would no longer be tolerated, Saudi officials said.
Critics charged that the crown prince was using the campaign to consolidate power by punishing potential rivals and seizing control of key businesses.
The attorney general's statement Tuesday did little to illuminate an episode that was cloaked in mystery, with officials refusing to provide details such as the names of detainees or the specific charges they faced.
And the government's zeal to reach financial settlements fed suspicions that it was pursuing a shakedown of its wealthiest citizens rather than a comprehensive attempt at reform.
Alwaleed was among the detainees who were released over the weekend after agreeing to unspecified financial settlements. The prince, chairman of global investment company Kingdom Holding, was held for more than two months with other prominent officials and businessmen at the Ritz-Carlton Hotel in Riyadh.
The fate of the 56 who remain in custody was not immediately clear. There are no more detainees at the Ritz-Carlton, the Reuters news agency reported, adding that some of those arrested are believed to have been moved to prison cells after refusing to admit wrongdoing and agree to financial settlements.
Hours before he was released Saturday, Alwaleed told Reuters in his opulent hotel suite that he was treated well in custody and that his case resulted from a misunderstanding. He praised the royal family and showed off the suite's gold-accented office, dining room and fully stocked kitchen, the news agency reported.
"I can only say I'm supporting the king and crown prince in all the efforts they're doing to really have a new Saudi Arabia," he told Reuters.
Alwaleed ranked as one of the world's most prominent investors, with holdings in companies including Apple, Twitter, Lyft and Citigroup.
In his statement, Mojeb, the attorney general, said authorities have finished reviewing the cases of those accused of corruption and that negotiations and settlements have been concluded. Accordingly, he said, the Public Prosecution Office decided to release those against whom there was insufficient evidence and those who reached settlements after they "admitted to the corruption allegations against them."
But the statement did not say how many people were in each category, leaving open the possibility that hundreds of detainees were, in fact, innocent.
It said the settlements were estimated to total more than 400 billion Saudi riyals ($106.6 billion) and consisted of "various types of assets," including real estate, commercial entities, securities and cash. No other details were immediately provided.
The campaign was billed as part of a modernization effort that would diversify Saudi Arabia's economy and encourage private investment from regional and Western investors. But analysts said the arbitrary nature of the arrests may have hurt that effort.
The crown prince's defenders argue that far-reaching changes are needed to ensure that the kingdom remains viable in the face of overwhelming reliance on declining oil revenue, a bloated government bureaucracy that employs the majority of working Saudis and a vast network of royal relatives dependent on the kingdom's largesse.
Branigin reported from Washington.