Authorities in Saudi Arabia are demanding $6 billion from Prince Al-Waleed Bin Talal, one of the richest men in the world, in return for his release after he was arrested in an anti-corruption purge last month in Riyadh.

The prince, who is the 57th richest man in the world, was one of dozens of businessmen, royals and government officials detained last month in the capital’s Ritz Carlton hotel in a move led by the country’s crown prince Mohammad Bin Salman.

Many of the others have since been released, with reports that many have paid for their freedom, but the fee demanded for Prince Al-Waleed is believed to be one of the highest.

Allegations levelled against Prince Al-Waleed included extortion, bribery and money laundering. Prince Al-Waleed is believed to be worth some $18.7 billion, and has accrued a vast portfolio that includes holdings in Citi Bank, Disney, Twitter and London’s Savoy hotel.

But he has reportedly refused to pay any such fee for his release, claiming that paying such a fee would amount to an admission of guilt. It is also believed that the fee could lead to the dismantling of much of the business empire he has spent his life building.

A source close to the prince told The Wall Street Journal ““He wants a proper investigation. It is expected that al-Waleed will give [Prince Bin Salman] a hard time,”