Madonna has cancelled performances in Israel after a series of threatening letters from “an unnamed Palestinian group:” Terror threat: We’ll kill Madonna. (Hat tip: Ethel C.)

The singer was terrified by a blitz of poison-pen letters.

Madge “freaked out” when she learned of a terrorist plot to kill her two young children if she performed in Israel.

She first planned to defy the extremists but cancelled after the unnamed Palestinian group mentioned details about Lourdes, seven, and three-year-old Rocco in a series of threatening letters.

A source said: “The notes were unbelievably scary. Madonna is a strong woman but she freaked out when her kids were mentioned. ”At first she was prepared to go on stage anyway and hire extra security. But she was not ready to take chances with her kids — they are her whole world.“

The threats were sent to the singer’s offices in Los Angeles. They became more frightening as they displayed in-depth knowledge of the star’s closest aides.

The source added: ”It became clear that these people were not messing around — they even knew intimate details like who her personal staff are. She thought she was being targeted because of her Jewish Kabbalah religion. But this group were threatening her because she represents many things they hate about the West.”