A total of 2,284 Saudis have joined terrorist groups outside the country over the past four years, an Interior Ministry spokesman said.
The spokesman, Maj. Gen. Mansoor Al Turki, said 645 of them have returned to Saudi Arabia, but the statuses of the others are unknown.
It is hard to know how many of them are alive, Al Turki told on Thursday.
Families of Saudis who died in suicide bombings are usually notified by representatives of the ISIS terror group that hired them.
ISIS among citizens of Saudi Arabia have much supporters. Government and al-Saud royal family accused of supporting armed rebels in Syria and Iraq.