Saudi Arabia has detained 11 princes as well as several current and former ministers, amid an anti-corruption crackdown by King Salman.
Among those to be held was the prominent billionaire businessman Prince Alwaleed bin Talal, a nephew of the Saudi monarch, who is chairman of Kingdom Holding, one of the largest shareholders in the banking giant Citigroup which also holds a stake in Twitter.
The head of the powerful National Guard and son of the late King Abdullah, Prince Miteb bin Abdullah, was also detained in the sweeping purge which consolidates the power of heir to the throne, Crown Prince Mohammed bin Salman.
The crackdown came after King Salman announced the creation of a new anti-corruption committee late on Saturday night, headed by 32-year-old Prince Mohammed.
State-run TV said the committee was created "due to the propensity of some people for abuse, putting their personal interest above public interest, and stealing public funds", after long-standing public complaints about abuse of power.
King Salman said in broadcast comments: "Laws will be applied firmly on everyone who touched public money and didn't protect it or embezzled it, or abused their power and influence. This will be applied on those big and small, and we will fear no one."
In what could be viewed as approval of the arrests, the kingdom's most senior clerics have said it is an Islamic duty to fight corruption.
The Saudi government says the newly established committee has the right to issue arrest warrants, impose travel restrictions and freeze bank accounts, as well as trace and prevent the transfer of funds or the liquidation of assets.
Experts have said the aim of the crackdown was not to tackle corruption, but to remove any likely opposition to Prince Mohammed's reforms, which include lifting a ban on women driving and opening up the conservative state to tourists.
An economist at a major Gulf bank, who did not wish to be identified, said: "It's about consolidating power and frustration that reforms haven't been happening fast enough."
Financial analysts said news of Prince Alwaleed's arrest saw shares in Kingdom Holding plummet by nearly 10%.