On Monday, King Abdullah of Saudi Arabia will be departing for the United States in order to receive medical treatment for his back illness that has worsened due to a blood clot.

The deteriorating health condition of the King has raised concerns regarding the subsequent successor of the world’s leading oil exporting country.

The eighty-six-year old monarch has a blood clot around a ruptured disc in his back and for its urgent treatment he had to cancel a ministers' meeting and also handed over the responsibility of administering the annual Muslim pilgrimage to Mecca to Prince Nayif ibn Abdulaziz, the Interior Minister.

Also, Abdullah has given up the position as the head of the National Guard, which has now taken up by his son, Prince Muteb. In his absence, Crown Prince Sultan, 82, who had been recovering in Morocco from a cancer-like disease has arrived back to be the acting king.

There is great likelihood that Nayif, an Islamic conservative, who was made second deputy Prime Minister in 2009, would be the successor of Abdullah after his demise, as believed by many analysts.

Mustafa Alani, Senior Advisor at the Gulf Research Center in the United Arab Emirates said, "There is no dispute in the line of succession. It's the king, then the crown prince and then Nayif”.