Israel is meant to remove dozens of settler outposts in the occupied West Bank not formally authorised by the government under a US-backed plan for peace with the Palestinians, but has failed to do so.
Datya Yitzhaki, a former Gaza settler and spokeswoman for the settler group called the Land of Israel Faithful, said on Tuesday, hundreds of youths had begun building wooden and stone houses and pitched tents at sites close to a dozen older settlements.
She said: "We intend to expand and build on these, we will build on what has been destroyed and show that settlement will resume."
An Israeli military source said the army was treating it as a protest of tent encampments and that the settlers had said they would eventually leave.
Nabil Abu Rdaina, a spokesman for Mahmoud Abbas, the Palestinian president, said that "settlement activities severely hurt Palestinian efforts to maintain calm".
He urged Israel "to cease these activities and uproot the outposts".
Some of the settlers were among those evicted by Israel from the Gaza Strip before it withdrew from the coastal territory in September after 38 years of military rule.