WASHINGTON • Prince Alwaleed bin Talal, detained since early last month in a corruption probe, faces a demand from Saudi Arabian authorities of at least US$6 billion (S$8.1 billion) to win his freedom, the Wall Street Journal reported.

The price being demanded is among the highest sought for those who have been arrested, the newspaper reported, citing people familiar with the matter.

Prince Alwaleed, 62, is the 57th-richest person in the world, with a US$18 billion fortune, according to the Bloomberg Billionaires Index.

He is known internationally for investments in companies including Citigroup, Apple and Twitter.

The Journal reported that Prince Alwaleed is talking with the government about accepting as payment for his release a large piece of his conglomerate, Kingdom Holding.

Kingdom Holding is listed on the Saudi stock exchange and has a market value of almost US$9 billion.