The desecration of the graves of assassinated Israeli Prime Minister Yitzhak Rabin and his widow has been blamed on ultranationalists opposed to a Gaza pullout plan.
Authorities said vandals at the weekend had scrawled "murderous dog" in Hebrew on the tomb of Mr Rabin, who was assassinated in 1995 by a far-right Jew incensed by his land-for-peace deals with the Palestinians.
The name of Rabin's wife, Leah, who died of cancer in 2000, was sprayed over on an adjacent headstone.
The defacing of the graves, in the Jewish state's most revered military cemetery at Mount Herzl in Jerusalem, stirred new Israeli fears of civil strife ahead of a planned withdrawal from the occupied Gaza Strip this summer.
Jewish ultra-nationalists opposed to Prime Minister Ariel Sharon's plan to "disengage" from the Palestinians by leaving some occupied land have stepped up their protests.
"We are not dealing with the perpetrators of the previous crime but with the perpetrators of the next one," Mr Ran Cohen of the leftist Yahad party told the Jerusalem Post, alluding to concerns that Mr Sharon could also be targeted for assassination.
Polls show most Israelis support Mr Sharon's plan to evacuate all 21 Jewish settlements in Gaza and four of 120 in the West Bank starting in July. It would be the first removal of settlements from occupied land Palestinians want for a state.
However many right-wing Israelis oppose giving up an inch of territory Israel captured in the 1967 Middle East war. They see the land as a Biblical birthright and any withdrawal as a reward for Palestinian militants who have waged an uprising since 2000.