Speaking at the Hamas political congress on Monday, Haniyeh criticized the Saudis for keeping Palestinians in prison simply because of their ties with the resistance movement.
In March a Saudi court held the first hearing in the case of 68 Palestinian and Jordanian detainees.
The detainees are charged with “supporting terrorism and financing it” and belonging to “a criminal terrorist entity”.
Senior Hamas official Muhammad al-Khudari and his son Hani, who were arrested last April, were among those who stood trial.
Al-Khudari represented Hamas in Saudi Arabia between the mid-1990s and 2003. He has held other important positions in the Palestinian resistance movement as well.
Saudi Arabia’s repressive measures against the Palestinian resistance movement as well as those seeking to collect donations for people living in the Israeli-blockaded Gaza Strip come as the kingdom and Israel are believed to be planning to publicize their secret ties.