Deposed Saudi crown prince Bin Nayef reportedly placed under house arrest, barred from travel abroad

The recently deposed heir to the throne of Saudi Arabia has reportedly been confined to his palace and barred from traveling abroad after he was replaced by the king's son as the crown prince.

Mohammed bin Nayef, who was also relieved of his role as interior minister a week ago, has effectively placed under house arrest in the coastal city of Jeddah, four current and former US officials and Saudis close to the royal family told The New York Times in a report published on Wednesday.

King Salman, 81, has named his son Mohammed bin Salman crown prince after firing Mohammed bin Nayef, whose counter-terrorism expertise had made him a favourite of previous US administrations.

An unnamed Saudi source told the newspaper that the restrictions had been imposed immediately after Mohammed bin Salman's promotion.

"Mohammed bin Nayef returned to his palace in Jeddah to find that his trusted guards had been replaced by guards loyal to Mohammed bin Salman... since then, he has been prevented from leaving the palace," the source said.

Over the past two years Mohammed bin Salman, the architect of the disastrous war in Yemen, has accumulated vast powers at the expense of Mohammed bin Nayef, 57.

A Saudi official told Reuters on Thursday that the reports of Mohammed bin Nayef's captivity were "100 percent" untrue.

Bin Salman's eventual rise has been long-predicted, but the timing of the appointment, in the midst of the largest Gulf diplomatic crisis in several years, will be sure to raise eyebrows.

The young prince is seen as close to the US administration of Donald Trump and is thought to be behind Riyadh's ratcheting up of tensions with Iran and its attempted isolation of Qatar.

Saudi media has portrayed a smooth transition of power between the two princes.

Saudi news channels have repeatedly aired footage of the younger Mohammed bin Salman kissing the hand and bowing to his older cousin Mohammed bin Nayef, who offers his congratulations.

Top royals and clerics to ordinary citizens, Saudis far and wide have pledged obedience and allegiance to their new future monarch - including fast food restaurants such as McDonald's.