Mohammad al-Khoudary had been a resident of Saudi Arabia for decades before his abduction in April. The Palestinian movement says attempts to release have been unsuccessful so far.
The Palestinian movement Hamas has confirmed that one of its senior leaders has been detained by Saudi Arabia since April without explanation.
Mohammad al-Khoudary had lived in the country for three decades before his arrest by Saudi security forces, the group said
Hamas had not released information about the “reprehensible” arrest until now to allow for mediation efforts to continue, it said in a statement, adding the efforts had yet to “bear fruit” .
Saudi Arabia has not explained its reasons for the arrest but the move comes amid burgeoning ties between Riyadh and Tel Aviv.
Though full diplomatic relations have not been established, Israel and Saudi Arabia are believed to have come together behind the scenes on a number of issues, such as their shared belief that Iran poses a threat to their interests and over the Palestinian issue.
According to the Euro-Mediterranean Monitor for Human Rights, a Geneva-based group, Saudi Arabia is holding 60 Palestinian prisoners.
The NGO said it had testimony from 11 Palestinian families who have had relatives forcibly disappeared while visiting or staying in Saudi Arabia.
"The campaign in Saudi Arabia of arresting Palestinians is but one in a long series of human rights violations in the country,'' said Euro-Med’s communication and media officer, Selin Yasar.
Former prisoners have complained of conditions inside the prisons, where they say they were deprived of sleep, medical conditions and subject to poor treatment.
Euro-Med some detentions had taken place during pilgrimages but news of these disappearances rarely leaked out because families were scared of repercussions from the authorities in Saudi Arabia.
Riyadh has long been accused of human rights abuses but there has been a particular focus on the country’s transformation under Crown Prince Mohammed bin Salman.
While the prince has loosened some social restrictions, such as allowing women to drive and opening cinemas, accusations of rights violations continue to plague the country.