RIYADH (Reuters) - Saudi businessman Amr Dabbagh and two management consultants have been released more than a year ago after their detention in a corruption crackdown which has shaken investor confidence in the world’s top oil exporter, seven sources said on Wednesday.

Scores of princes, top officials and businessmen were held in Riyadh’s Ritz-Carlton Hotel on the orders of Crown Prince Mohammed bin Salman in November 2017. Critics decried the campaign as a shakedown and power play.

Dabbagh is chairman and chief executive of a family conglomerate, and for years headed the Saudi Arabian General Investment Authority, which aims to attract foreign investment to the country.

The others released this week, according to the sources who requested anonymity, are Hani Khoja and Sami al-Zuhaibi. They are co-founders of the consultancy Elixir, acquired in 2017 by McKinsey, which the Saudi government has contracted to help design economic and social reforms that Prince Mohammed is pushing to end dependence on oil revenues.

The men could not be reached, and the Saudi government communications office did not immediately respond to a request for comment. The Wall Street Journal first reported their release.

The allegations against them and the terms of their release remain unclear. The public prosecutor has not provided an update on the anti-corruption campaign in nearly a year, deepening uncertainty in the local and international business communities.

Most of those detained were freed within a few months after reaching settlements the authorities said would net more than $100 billion. Some were reportedly tortured, which the government denies.

More people were later arrested and some are still believed to be detained, including former Economy Minister Adel Fakieh, Saudi Binladin Group Chairman Bakr bin Laden, and Saudi-Ethiopian billionaire Mohammed al-Amoudi.

Prince Mohammed told Bloomberg in October that only eight people were still being held, and the finance minister told Reuters last month that cash settlements had generated some $13 billion in 2018 and would net “not significantly” less this year.

One former detainee, billionaire investor Prince Alwaleed bin Talal, has said he reached an agreement with the government for his release, without disclosing details.

Another, former Finance Minister Ibrahim al-Assaf, was appointed foreign minister last month. A Saudi official told Reuters at the time of his release that Assaf had been cleared of any wrongdoing and without making any payment to the state.