RIYADH, Saudi Arabia—Months after the start of an anticorruption crackdown, Saudi authorities are still holding a senior prince and several dozen businessmen and former officials in detention and recently have made new arrests, government officials said.
Some of the detainees have been beaten and deprived of sleep while being questioned, officials and people close to the detainees said. In some cases, these people said, those in custody haven’t been charged with crimes and have been permitted little or no contact with relatives or lawyers.
Many are being held at a maximum-security prison outside the capital, while others are being housed in palaces that have been converted into detention centers, two government officials said. The officials acknowledged that some prisoners had been subjected to rough treatment.
Spokesmen for the Saudi government didn’t respond to requests for comment. The country’s deputy attorney general has said some detainees face charges that go beyond corruption and could be tried in courts that specialize in cases of national security and terrorism.
None of the detainees could be reached for comment. People close to several of them said authorities had raised the prospect of treason or terror charges, which could lead to prison or the death penalty, as a tactic aimed at pressing for untrue confessions or financial settlements.
Hundreds of prominent Saudis were arrested in November and detained at the Ritz-Carlton hotel in Riyadh. Most were released after agreeing to make payments Saudi officials say totaled more than $100 billion.
The Saudi government has described the campaign as a way of ridding the country of corruption and leveling the commercial playing field as Crown Prince Mohammed bin Salman works to revamp the economy and attract foreign investment and talent.
Corruption has been endemic in the kingdom, where much of the economy depends on state spending and a large royal family made rich by oil long operated with few limits. In March, King Salman, Prince Mohammed’s father, established new departments in the attorney general’s office to prosecute corruption cases.
Critics of the government say the new arrests and continued detentions are an effort by Prince Mohammed to consolidate power and sideline potential opponents one year after his father installed him as the country’s de facto ruler in a precedent-breaking move. The government denies the accusation.
Under Prince Mohammed, who runs Saudi Arabia day to day, the government has worked to open up a religiously conservative traditional society with steps such as allowing women to drive and opening cinemas, while at the same time jailing critics, including clerics and rights activists.
Those still in custody include some of Saudi Arabia’s richest men, and some who once held powerful government positions until their arrests last November. Among them are Mohammed al-Amoudi, a Saudi-Ethiopian billionaire; Bakr bin Laden, the chairman of the construction giant Saudi Binladin Group; Amr al-Dabbagh, former head of Saudi Arabia’s investment agency; and Adel Fakeih, a former economy minister and once a trusted aide to Prince Mohammed.
Also detained is a senior royal, Prince Turki bin Abdullah, who served as governor of Riyadh and is a son of the previous monarch, King Abdullah.
A Saudi official in November said the prince was accused of corruption linked to a project to build a subway in Riyadh. He hasn’t been charged and the exact accusations he faces remain unclear, according to a person familiar with the matter, who cast the prince’s arrest as a political move intended to sideline a potential rival of Prince Mohammed.
Some detainees released from the Ritz have been subjected to travel bans and some have had to wear ankle monitors, people close to those former detainees said. Several have become outspoken advocates for Prince Mohammed’s approach. At least one has gone into business with the government.
The Saudi government’s investigation into some prominent business families is still under way, Saudi government officials said. In recent days, three billionaires from the Mahfouz family, a prominent Saudi banking group, have been detained for undisclosed reasons, the officials said.
Other executives have secretly negotiated settlements to avoid detention in recent weeks, these officials said.
Since the Ritz was closed as a detention centerand reopened as a hotel in late January, there has been nearly complete official silence on the cases of 56 suspects who didn’t agree to a settlement.
The Saudi government wants to avoid the publicity of the Ritz episode “and will do things more quietly with any new arrests,” a person familiar with the matter said.
Mr. Dabbagh, the former head of the Saudi investment agency and a Jeddah businessman who heads one of the country’s biggest conglomerates, has been subjected to physical and psychological abuse in detention, people familiar with the matter said.
He initially rejected a government request to hand over 70% of his assets and 50% of all future revenue in exchange for his freedom, a person close to him said.
“There are no charges, no evidence, no interviews with family members, executives of his company,” that person said. “He refuses to settle because that would make him guilty, and he isn’t.”
Saudi authorities have discussed charging Mr. Fakeih, the former economy and planning minister, with orchestrating a plot to separate the Hijaz region from the rest of Saudi Arabia, government officials said. People close to Mr. Fakeih said the accusations were baseless.
—Benoit Faucon in London contributed to this article.