Israel currently holds some 8,500 Palestinian security prisoners in its jails, a spokeswoman for the Israeli human rights group B'Tselem said Monday.

As of July 30, the number of Palestinian security prisoners in the Israel Prisons Service (IPS) stood at 8,472, B'Tselem said.

They include 5,176 Palestinians serving a sentence, 2,605 Palestinians awaiting or undergoing trial, and another 691 Palestinians held in "administrative detention."

Administrative detention is a controversial, special legal ground for holding suspects who are deemed a "security threat" without trial for extendable six-month periods.

About 30 Palestinians more are held in Israeli army detention facilities.

B'Tselem said it receives data on the numbers of Palestinians held in Israeli jails on a monthly basis from both the Israel Prisons Service and the Israeli army.

"We checked with the Red Cross and our numbers are correct," spokeswoman Sarit Michaeli told Deutsche Presse-Agentur dpa.

Israel is holding the 8,505 Palestinians for a variety of security offences, ranging from involvement in shooting and bomb attacks, possession of or supplying weapons to militants, to membership in militant organizations declared illegal in Israel.

The organizations include the armed wings of Palestinian President Mahmoud Abbas' Fatah movement, the radical Islamic Hamas ruling Gaza, and the smaller Islamic Jihad and leftist Popular and Democratic Fronts for the Liberation of Palestine(PFLP and DFLP).

About 1,500 Palestinians are also imprisoned in Israel for criminal offences such as car thefts, robberies, drugs and rape, but these criminal detainees are not counted among the "security prisoners," Michaeli explained.