Graffiti was found Tuesday on a rabbi's tomb in northern Israel in what appeared to be an act of revenge following a recent string of similar attacks targeting Arabs.
A swastika was painted on the tomb near the town of Karmiel, along with the words: "The price to be paid... will be paid," police spokeswoman Louba Samri told AFP.
It appeared to be a reference to "price tag" attacks carried out by Jewish extremists against Palestinians in the occupied West Bank and against Israel's Arab citizens.
Such attacks -- generally involving vandalism, the slashing of car tyres or small-scale arson -- were originally carried out in response to Israeli moves to curtail settlement construction but in recent years have grown into a more general phenomenon, raising alarm among some Israeli officials.
Over the past week, vandals sprayed racist graffiti over two mosques in northern Israel and also targeted an ancient Christian church on the Sea of Galilee, damaging crosses and threatening clergy.
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A Muslim graveyard was also defaced and two dozen olive trees were chopped down in the West Bank.
On Monday, Defence Minister Moshe Yaalon said Israel must "fight with an iron fist against the terror which is wrongly called 'price tag' -- an ugly phenomenon which has no connection to Jewish values or morals."
His remarks came as Israeli police said they had arrested seven Jewish minors over racist acts and vandalism.
Four are suspected of spraying racist graffiti at a building site by an Arab village near Jerusalem, and another three were picked up for spitting at a priest by Jerusalem's Old City and for carrying flags scrawled with the words "revenge" and "price tag".
Such arrests are rare, however, and last week the US State Department for the first time included mention of price tag attacks in its global report on terror, saying such incidents were "largely unprosecuted".
And on Sunday, Israeli Justice Minister Tzipi Livni said she would back the idea of defining such acts as "terrorism".