Saudi Arabia 'must come clean' over senior royal's 'detention'
Mohammed bin Nayef was reportedly removed from being successor to the throne in a palace coup last month, which saw 31-year-old Mohammed bin Salman - son of the current monarch - take his place.
"Reports that Mohammed bin Nayef is under a travel ban and home detention without due process are bitterly ironic given his role in imposing similar arbitrary restrictions on thousands of Saudis," said Sarah Leah Whitson, HRW's Middle East director.
HRW on Thursday also called for the kingdom to end the arbitrary use of travel bans and detention of Saudi citizens.
"The Saudi government needs to call a halt to officials' arbitrary abuses of power."
Following Bin Nayef's removal from his post, it was reported last week that the 57-year-old royal had been placed under house arrest.
HRW urged Riyadh to clarify the prince's status in a letter sent to Saudi Foreign Minister Adel al-Jubeir.
Saudi officials have not yet responded to the request from HRW.
"Extended detention without charge or trial or without an appearance before a judge is arbitrary, and violates both Saudi law and international human rights standards," HRW said in its statement.
Earlier this month, sources close to the palace and US officials revealed details of the events that allegedly led to Bin Nayef's replacement as crown prince.
It is claimed the former security head was held against his will one night in June and pressured during to step aside in an interrogation that lasted until dawn.
The unnamed sources said that the prince's alleged painkiller addiction was exploited as a means of sweeping him aside in favour of Bin Salman - a young and ambitious prince whose current record includes Saudi Arabia's destructive war in Yemen and a U-turn on pay cuts to Saudi civil servants.