Former Israeli premier Yitzhak Rabin's grave has been defaced, the latest in a series of attacks police believe may be linked to ultra-nationalist Jews.
David Ben Gurion's grave was sprayed with the word Hitler
The slogan "murderous dog" in Hebrew was sprayed on his tomb in Jerusalem as well as that of his wife Leah.
Rabin was assassinated in 1995 by a right-wing Jew opposed to the Oslo peace accord with the Palestinians.
The graves of Zionist pioneer Theodor Herzl and the first Israeli PM David Ben Gurion were defaced last week.
Jerusalem police have formed a special team to investigate the incidents.
"We think that the extreme right wing is behind this," said Jerusalem police spokesman Shmulik Ben Ruby in remarks quoted by AFP.
The Rabins' and Herzl's graves are situated in the Mount Herzl national cemetery, where Herzl's grave had the words "Neo-Nazi Hail Beilin" scrawled on it in black paint last week.
Israeli politician Yossi Beilin heads left-wing Yahad that favours pulling Israeli settlers from the occupied West Bank and Gaza.
Security has been stepped up around Ariel Sharon
Ben Gurion's grave in the southern Negev desert was found with the word "Hitler" sprayed on it on Wednesday.
On Friday, the graves of 12 soldiers in Mount Herzl's military section were inscribed with the word Hitler.
The desecrations have provoked outrage and condemnation among Israeli politicians.
"These repugnant and shameful acts are perhaps the work of only one or two people who are mentally deranged but these are people who can shatter and destroy our way of life," said Deputy Prime Minister Shimon Peres.
Some reports say security cameras filmed the acts of desecration against the graves of the Rabins.
The incidents follow a spate of graffiti-writing in Jerusalem streets in recent weeks threatening Prime Minister Ariel Sharon for his plan to withdraw Israeli settlers and soldiers from the occupied Gaza Strip.
Fears have been voiced that the atmosphere of incitement which preceded Rabin's assassination is being replicated by opponents of the plan.
In February, Internal Security Minister Gideon Ezra called for the arrest of those threatening Mr Sharon and ministers who support Gaza withdrawal.
This followed specific death threats from right-wing Israeli extremists.
The Israeli intelligence services are meanwhile trying to head off any possibility of violence at the flashpoint mosque compound in Jerusalem's Old City.
Dozens of extra officers and cameras have been deployed at the site, known as the Temple Mount to Jews and al-Aqsa Mosque to Muslims.
Police have banned a rally called by ultra-nationalist Jews at the compound which had been planned for 10 April.
Starting on 20 July, Israel is planning to pull all of its 7,000 settlers from Gaza and the troops that protect them, as part of a disengagement plan.
Israel will maintain control of Gaza's borders, coastline and airspace.