Saudi Arabia’s Crown Prince Mohammed bin Salman’s recent political purge raises concerns and remains unclear but does not appear to amount to mass arrests, U.S. Secretary of State Rex Tillerson told reporters on Friday.

Saudi Arabian authorities have made further arrests and frozen more bank accounts in an expanding anti-corruption crackdown on the kingdom’s political and business elite, sources familiar with the matter said on Wednesday.

Saudi Arabia’s Attorney General said on Monday detailed questioning of individuals detained on the back of an anti-corruption probe had taken place and “a great deal of evidence” had already been gathered.

U.S. President Donald Trump on Monday endorsed a move by Saudi Arabia’s future king that tightened his grip on power through the arrests of royals, ministers and investors in an anti-corruption purge.

Saudi Arabia’s future king has tightened his grip on power through an anti-corruption purge by arresting royals, ministers and investors including billionaire Alwaleed bin Talal who is one of the kingdom’s most prominent businessmen.

The deputy governor of Saudi Arabia’s southern Asir province and several colleagues were killed in a helicopter crash on Sunday, Saudi state TV Ekhbariya reported.

Bribery, embezzlement, money laundering and abuse of power are among the accusations levelled against dozens of Saudi princes, officials and businessmen detained in an anti-corruption probe, a Saudi official told Reuters on Monday.

Saudi Arabia has arrested dozens of senior figures including princes, ministers and a top business tycoon, with authorities on Sunday pledging "fair" justice after a sweeping purge seen as consolidating the crown prince's hold on power.