Campaigners wrote on Facebook that the fate of Sheikh Al-Hawali, his sons and brother remain unknown following their enforced disappearance after being arrested and detained without charges and without legal basis.

Details of why the Sheikh was held by authorities will be revealed by activists in the comping days, the statement continued.

The campaign called on human rights activists around the world and scholars to support the release of the Sheikh and his sons.

Saudi authorities arrested Al-Hawali and a number of his children in July accusing him of criticising the toyal family’s policies.