"Just ahead of the anniversary of Rabin's murder, the Shin Bet sees in the group we're talking about on the extreme right a willingness to use firearms in order to halt diplomatic processes and harm political leaders," Shin Bet chief Yuval Diskin said.
"The Shin Bet is very concerned about this."
Diskin spoke at the weekly meeting of the Israeli Cabinet, and his statement was released by another meeting participant who spoke on condition of anonymity because the session was closed.
Opening the meeting, Prime Minister Ehud Olmert warned of growing lawlessness among West Bank settlers. Groups of settlers have clashed repeatedly with Israeli police, soldiers and Palestinians in the past week over the evacuation of an unauthorized outpost they set up in the West Bank city of Hebron.
Alongside law-abiding settlers, Olmert said, "there is also a significant group of people that has cast off all authority and behave in a way that threatens the correctness of the rule of law, not only in the area they live in, but in the overall atmosphere of the state of Israel, and that is unacceptable and we are not willing to live with it."
Olmert said the government would establish a special team entrusted with enforcing the law among settlers.
Rabin's assassination on Nov. 4, 1995, continues to reverberate.
On Friday, two Israeli TV stations pulled telephone interviews with his assassin, Yigal Amir, after they were roundly condemned for giving him exposure.
In excerpts of the interviews, Amir's first, he said he had been inspired to commit the assassination by criticism of Rabin's peace moves that he heard from ex-military politicians like Ariel Sharon, Israel's former prime minister. Sharon has been in a coma since suffering a stroke in January 2006.
Settlers and Palestinians clashed again in Hebron on Sunday when hundreds of Palestinians held a protest against the presence of Israeli troops and settlers in the city. The Palestinians scuffled with Israeli soldiers, and settlers pulled down three Palestinian flags hung by the protesters and burned one of them.