JERUSALEM  Prime Minister Benjamin Netanyahu of Israel said Sunday that several Jewish settlement blocs in the West Bank would always remain part of Israel, a comment that upset the Palestinians even as the Obama administration’s Middle East envoy was trying to coax them back into peace talks.

Although Israel has long insisted on maintaining a permanent hold over certain groups of settlements, including those Mr. Netanyahu referred to Sunday, his remarks struck a jarring note on a day when the American envoy, George J. Mitchell, shuttled between Israeli and Palestinian leaders on a so-far unsuccessful mission to restart negotiations that have been stalled for over a year.

Mr. Netanyahu took the opportunity of the approaching holiday of Tu Bishvat, a Jewish arbor day, to reaffirm Israel’s claim to the Etzion bloc of settlements just south of Jerusalem. “Our message is clear,” he said during a tree-planting ceremony there. “We are planting here, we will stay here, we will build here. This place will be an inseparable part of the State of Israel for eternity.”