"Stop sucking our blood," the letters say. "Pack up your stuff and your shtreimels and go to Brooklyn." The Knesset Officer has launched an investigation into the source of the letters, which were sent to MKs Uri Maklev and Moshe Gafni of United Torah Judaism.
"We, the enlightened people of Israel, demand that you, people of darkness, stop living at our expense by studying without working, and get out of our lives," the letters say.
"If you continue to squeeze out funds at our expense you will pay a hefty price, as we will fight you physically and not just through demonstration. You will feel our wrath on your selves and your synagogues. We will make your lives miserable and attack you in your cities and neighborhoods."
The letters, signed with a word play on 'price tag policy', a name given by settlers to acts of revenge against Palestinians in the West Bank. Beneath was a picture of a skull wearing a traditional hat and side-locks.
The letters were taken in by the Knesset Officer, but the white substance has not yet been identified.
Gafni's public relations adviser said in response to the letters that "it was clear to us that the rabid incitement against the haredim would lead to such maneuvers and even violence".
"It's too bad there is no real dialogue in Israeli society, only hate campaigns," he added.
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