In a statement, the European People’s Party (EPP) called for the immediate disclosure of the fate of bin Nayef and his protection from murder by the heir to the Saudi throne, the Doha-based Al Jazeera broadcaster reported on Tuesday.
The group said it has obtained evidence suggesting that bin Nayef’s health condition has deteriorated in Saudi jail.
The EPP described bin Nayef’s continued detention as a source of concern for Europe, urging bin Salman to refrain from eliminating his critics and political rivals.
Bin Salman became Saudi Arabia’s crown prince on the back of a 2017 palace coup that ousted bin Nayef.
Since his ouster, bin Nayef has effectively been under house arrest and prevented from leaving the kingdom.
In March, he was arrested as part of a renewed purge of royal family members over an alleged coup attempt to unseat King Salman bin Abdulaziz Al Saud and his son.
The Washington Post revealed earlier this month that bin Salman was preparing a set of corruption and disloyalty charges against bin Nayef to demand a $15-billion settlement from the detained prince.