At least 20 princes have reportedly been detained in a stunning purge of princes, including King Salman's brother Prince Ahmed bin Abdulaziz and his nephew, on suspicions of plotting a coup against Crown Prince Mohammad bin Salman, often referred to as MBS.

A report by the Middle East Eye (MEE) said Saturday that: "Up to 20 princes have been arrested for allegedly being part of a coup to overthrow the crown prince." The MEE report claimed that four names had already been ascertained, including: "Prince Ahmed; his son Prince Nayef bin Ahmed bin Abdulaziz, Head of Land Forces Intelligence and Security Authority; the former Crown Prince Mohammed bin Nayef; and his half brother Nawaf." King Salman's nephew is "the highest-ranking member of the Saudi Armed Forces known to be arrested so far," the MEE report also said.

The arrests on Friday of the king's younger and much-loved brother, Prince Ahmed, as well as the king's nephew and former counterterrorism czar, Prince Mohammed bin Nayef, came after a number of observations had been made that were provocative to leadership, one insider in Saudi Arabia with knowledge of the arrests reported.

Both princes had served previously in the post of interior minister, overseeing security and surveillance inside the kingdom.

The move came as a surprise, given that Nayef, 60, was widely known to be under close surveillance since he was shunted out of the line of succession by the king's son in mid-2017, a person close to the royal court said.

The arrest of Prince Ahmed, 78, was also unexpected as he is the king's full younger brother and also a senior member of the ruling Al Saud family.

Prince Ahmed, however, has long held unfavorable views of the 34-year-old crown prince and was one of just a few senior princes to abstain from pledging allegiance to him when the young royal sidelined more senior princes to become first in line to the throne.

The Wall Street Journal first reported the arrests, quoting unidentified sources allied with the royal court as saying the princes were plotting a palace coup that would halt the rise of the crown prince. The Journal has reported that the sweep had since broadened to include dozens of Interior Ministry officials, senior army officers and others suspected of supporting a coup attempt.

The two people who talked to The Associated Press declined to characterize the actions by the two princes as a coup attempt and agreed to discuss the highly sensitive security matter only if granted anonymity.

One added that the arrests had been made to send a message to those in the royal family feeling disenfranchised to stop grumbling and toe the line, saying that if Prince Ahmed could be arrested, any prince could and would be. Prince Ahmed was seen as a person whom royals vexed with the crown prince's grip on power could look to, the person said. There has been no official comment from Saudi authorities on the arrests.

The crown prince has succeeded in a few short years at sweeping aside any competition from royals older and more experienced than him. He has also overhauled the most powerful security bodies to report to him.

Nayef is well-known and liked by U.S. intelligence officials for the efficiency of his past counterterrorism work against al-Qaida. As head of the Interior Ministry, he was a feared and towering figure who oversaw the long arm of the government that both prosecuted and closely monitored and jailed dissidents and critics of the kingdom.

After being removed from the role of the crown prince and replaced by the king's son, he was stripped of his power and closely monitored.

Prince Ahmed has been seen as critical of the crown prince, including telling protesters who were accosting him in London to ask the king and his son about the humanitarian disaster sparked by the war in Yemen. Religiously conservative, the prince also recently grumbled over the decision to close Islam's holiest site in Mecca to stymie the spread of the new coronavirus, according to one of the people familiar with the arrests.

The arrest of the two senior princes is most likely a preemptive move to manage risks to a transition from King Salman to his son, according to an analysis by Eurasia Group. Both princes were seen as possible alternatives to Prince Mohammed bin Salman.

The reports of a crackdown on senior royals who could pose a threat to the 34-year-old crown prince's ascension to the throne sparked speculation once again about the 84-year-old monarch's health and ability to rule. A U.S. official said King Salman appeared healthy and lucid in his meeting with U.S. Secretary of State Mike Pompeo on Feb. 20 in Riyadh. The two discussed the Saudi-led war in Yemen, efforts to counter Iran, the war in Syria and human rights issues.

As recently as Thursday, the king met with British Foreign Secretary Dominic Raab in Riyadh.

The crown prince has succeeded in consolidating power and cementing his place as the day-to-day ruler, in part through farreaching crackdowns on perceived critics or competitors.

The October 2018 killing of Saudi columnist Jamal Khashoggi by agents close to the crown prince inside the kingdom's consulate in Istanbul, however, damaged the prince's reputation globally.

Foreign investors were also rattled by an anti-corruption operation overseen by the prince in late 2017 that saw top royals, officials and senior businessmen rounded up and detained for up to several months in the luxurious Ritz-Carlton hotel in Riyadh and forced to sign over billions of dollars in assets in exchange for their freedom in secretive agreements.

The crown prince is popular among many in Saudi Arabia for pushing through bold reforms that have transformed life in the kingdom for many, including loosening severe restrictions on women and allowing concerts to be performed and movie theaters to open.

Still, his economic transformation plans have struggled to take off. The kingdom continues to rely heavily on oil for revenue, despite efforts to diversify. Oil prices have plunged amid the disruptions caused by the new coronavirus, signaling trouble for producers like Saudi Arabia. Foreign investors have thus been rattled by the prince's unpredictability.