Prince Mohammed bin Nayef and Prince Ahmed bin Abdulaziz are reportedly accused of treason.

Saudi Arabian authorities detained a brother and a nephew of Saudi King Salman in a move that extends a crackdown on royal relatives by his son Crown Prince Mohammed bin Salman.

Prince Mohammed bin Nayef and Prince Ahmed bin Abdulaziz al Saud were arrested on Friday and accused of treason, a person familiar with the matter said. Prince Mohammed’s brother, Nawaf, was also detained with him at a desert camp, the person said. The news was reported earlier Friday by the Wall Street Journal and the New York Times.

Since King Salman took power, senior Saudi princes have been sidelined in favor of his son Prince Mohammed, who has consolidated power to an unprecedented level by arresting princes and removing them from key posts as he took control of the kingdom’s ministries and institutions of power. Prince Mohammed bin Nayef had been in line to the throne and was the country’s interior minister before being stripped of his powers in 2017.

Later the same year, Prince Mohammed embarked on his most sweeping crackdown during his reign, ordering security forces to arrest senior princes and prominent businessmen in what was declared a crackdown on corruption. Billionaire Prince Alwaleed bin Talal was detained at the Ritz Carlton Hotel. Prince Miteb, son of the late King Abdullah, was removed from his post as head of the powerful National Guards.