Israeli police have arrested two men suspected of planting fake bombs in Jerusalem to try to disrupt plans to pull settlers out of the Gaza Strip.
There are fears ultra-sensitive sites could be attacked
The men, Jewish Israelis, were caught after leaving a backpack rigged with wires, police said.
The arrests come amid heightened fears that right-wing activists will step up attempts to sabotage the withdrawal.
A Jewish group meanwhile has called for a mass rally against the pullout at a highly sensitive Jerusalem holy site.
The group, Revava, says it wants at least 10,000 Jews to ascend the hilltop known to Jews as the Temple Mount and to Muslims as Haram as-Sharif on Sunday.
Fearing an eruption of violence, Israeli authorities have closed the site to non-Muslims, but Revava has vowed to defy the ban.
Jerusalem police spokesman Shmuel Ben-Ruby said the men who were arrested belonged to an outlawed ultra-nationalist group, Kahane Chai.
He said the backpack contained wiring, a note and cardboard, without elaborating on what was written on the note.
An Israeli police spokeswoman said some of those opposed to the Gaza withdrawal planned to distract the security services "so that they will not be able to carry out evacuations".
The arrests came a day after police in Jerusalem raised the level of alert in the city, amid growing fears of sabotage attempts by extremists.
Amos Gilad, a senior defence ministry official, said there were fears of an attack on the Temple Mount/Haram as-Sharif, but he said authorities would use "all means available, including unprecedented ones" to prevent it.
Revava leader Israel Cohen said supporters would try to enter the compound regardless of the ban.
"We reserve the right to pray at our holy site. We will arrive in masses... and we will in any case try to enter," the Associated Press news agency quoted him as saying.
Islamic leaders in Israel have called on Muslims to amass on the site to prevent Jews from entering.
The fate of the Temple Mount/Haram as-Sharif, where two large mosques stand above the ruins of two Biblical Jewish temples, is one of the most sensitive issues dividing Israel and the Muslim world.