Saudi Arabia has freed influential Prince Miteb bin Abdullah, following a "settlement" with authorities reportedly exceeding $1 billion, more than three weeks after he was detained in a sweeping anti-corruption purge.

The former National Guard chief was among more than 200 princes, ministers and businessmen who were rounded up earlier this month, as Crown Prince Mohammed bin Salman tightens his grip on power. Prince Miteb, once seen as a contender to the throne, is the most high-profile royal to be released so far as the government appears to be striking monetary settlements with some of the detainees in exchange for their freedom. "Yes, Prince Miteb was released [Tuesday] morning," a source close to the government told AFP, without outlining the terms of his release.

The prince was released after paying more than $1 billion in a "settlement deal" with authorities, Bloomberg News cited an unnamed official as saying. Saudi information ministry officials also could not confirm the development but posts on social media by members of the royal family suggested he had been freed. Princess Nouf bint Abdullah bin Mohammed bin Saud posted an old image of Prince Miteb on a verified Twitter account with the message: "Praise be to Allah. Peace be upon you."

In a similar post with the picture of a smiling prince, Princess Abeer bint Khaled bin Abdullah tweeted: "May god grant you a long life, give you health and keep you safe for us."

Before his arrest the 64-year-old son of the late king Abdullah was sacked as the head of the National Guard, an internal security force that has long been seen as a locus of tribal power.