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Saudi Arabia has detained dozens of princes, businessmen, senior military officials and top officials in luxury hotels, media has reported, as part of a major arrest sweep it claims is part of an anti-corruption probe.

A Saudi government official with close ties to security says 11 princes and 38 others are being held after the mass detentions overnight Saturday, including influential Saudi tycoon Prince al-Waleed bin Talal, one of the world's richest men.

Reports suggested those detained were being held at the Ritz Carlton in Riyadh, which only days earlier hosted a major investment conference with global business titans from the US, Japan and other countries.

A Saudi official told The Associated Press that other five-star hotels across the capital were also being used to hold some of those arrested.

Marriott International said in a statement that it is currently evaluating the situation at the Ritz-Carlton in Riyadh. "As a matter of guest privacy, we do not discuss the guests or groups with whom we do business or may be visitors of the hotel," the statement added.

Scale of arrests 'unprecedented'

The dramatic shake-up comes at a time of social and economic transformation in ultra-conservative Saudi Arabia, as Crown Prince Mohammed bin Salman steps up his reform drive for a post-oil era.

Shortly before the arrests, King Salman had ousted Prince Miteb bin Abdullah from his post as head of the National Guard in a series of high-profile sackings that sent shock waves through the oil-rich Gulf country.

Also purged were the navy chief and the economy minister.

Prince Miteb bin Abdullah is reportedly among those detained in the sweep, as is his brother, Prince Turki bin Abdullah, who was once governor of Riyadh. Both are sons of the late King Abdullah, who ruled before his half-brother King Salman.

Saudi Twitter accounts released several other names of those arrested, including Alwalid al-Ibrahim, a Saudi businessman with ties to the royal family who runs the Arabic satellite group MBC, Amr al-Dabbagh, the former head of the Saudi Arabian General Investment Authority, Ibrahim Assaf, the former finance minister, and Bakr Binladin, head of the Saudi Binladin Group, a major business conglomerate.

The mass arrests were hailed by pro-government media outlets as a sign Crown Prince Mohammed bin Salman was keeping his promise to tackle corruption, which has long plagued the highest levels of government.

The finance ministry said the anti-corruption probe "opens a new era of transparency and accountability", and enhances confidence in the rule of law and improves the kingdom's investment climate.

It is not clear what Prince al-Waleed or others are being investigated for.

Analysts say that the arrest of once-untouchable members of the royal family is the latest sign that bin Salman is moving to quash potential rivals or critics.