Israel's security forces have begun expelling extreme settlers from the West Bank in an effort to circumvent violent flare-ups next month, when the UN vote on a Palestinian state is expected to take place.

Twelve residents of Yitzhar were last week issued with orders limiting their movements. Three of them were ordered to remain on the settlement and not leave it. Nine others were banned from being in Yitzhar, with three of those banished from the West Bank entirely.

The orders are for periods of up to a year and the Shin Bet explained that they had been issued after it was understood that there was no other legal means to prevent the 12 settlers from disrupting security in the West Bank.

IDF officers have said in recent months that they believe that a number of men living in Yitzhar have carried out violent "price tag" attacks on Palestinian civilians in the area, including an arson attack on a house in the village of Hawara, from which a mother and three children only just escaped with their lives.

The Shin Bet's reluctance to reveal its intelligence-gathering methods meant that these suspects were not arrested. On Monday, two of the 12 who were served the restricting orders were arrested near Tel Aviv on allegations of vandalising Palestinian property, but the police and the Shin Bet would not say whether they were suspected of being the arsonists.

"My chief worry right now is that a attack by settlers will spark off a violent Palestinian backlash," said a senior IDF general recently. "With the Palestinians, we have things under control for now, but the settlers are the wild card that could change everything."