Crown Prince Mohammed bin Salman launched a purge against his chief royal rival, his uncle Prince Ahmed bin Abdelaziz, because he intends to become king before the G20 summit in Riyadh in November, sources briefed about the plans have told Middle East Eye.

Bin Salman, known as MBS, will not wait for his father King Salman to die because his father's presence gives legitimacy to the son, and he wants to use the summit in November as the stage for his accession to the throne. 

Instead, MBS will force his father, who suffers from dementia but is in otherwise good health, to abdicate, the sources said. 

This will finish the job started when MBS ousted his elder cousin Prince Mohammed bin Nayef from the position of crown prince, the sources said.

"He wants to be sure while his father is there, he becomes the king," one source said. Over the weekend pictures were released of King Salman greeting ambassadors, to disprove rumours sparked by the purge that the king had died. Sources at the King Faisal Hospital dedicated to the care of members of the royal family also dispelled those rumours.

Before his arrest on Friday, Prince Ahmed, the king's younger full brother, was given one last chance, after years of public opposition, to come aboard the MBS project, and he refused, the sources said.