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.

The prime minister of Israel, Benjamin Netanyahu, helped plant a tree in a West Bank settlement near Jerusalem on Sunday.

Mr. Netanyahu spoke about the Etzion bloc on Sunday.

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.”

The Etzion settlements were settled by Jews before the Israeli state was established in 1948. The area became part of the West Bank under Jordanian control after the 1948 war, and the settlements were destroyed. Some settlers returned there immediately after Israel captured the territory from Jordan in the 1967 war, and the settlements were rebuilt.

Earlier, in remarks before the weekly cabinet meeting in Jerusalem, Mr. Netanyahu said he would also plant saplings in Maale Adumim and Ariel, two large settlement-cities that Israel also intends to keep.

He also said that Mr. Mitchell, with whom he had just met, presented what he described as “some interesting ideas” for resuming the diplomatic process with the Palestinians.

“We are very much interested in doing so, and I expressed my hope that these ideas bring this about,” Mr. Netanyahu said.

But Nabil Abu Rudaineh, a spokesman for the Palestinian president, Mahmoud Abbas, who met with Mr. Mitchell in Jordan on Sunday, said that it was “premature to talk about a real breakthrough,” according to the official Palestinian news agency, WAFA.

Mr. Abu Rudaineh added that Mr. Abbas had reassured Mr. Mitchell of his commitment to peace.

But the spokesman also condemned Mr. Netanyahu’s tree-planting as “an unacceptable act that destroys all the efforts being exerted” by Mr. Mitchell, The Associated Press reported.

The Palestinians claim all of the West Bank, as well as Gaza and East Jerusalem, for a future Palestinian state, although they have expressed readiness for minor border adjustments in return for commensurate swaps of land.

Mr. Netanyahu has offered to begin peace talks without preconditions, and in a gesture to get the Palestinians to agree, in November he announced a halt to all new residential construction in the West Bank settlements for 10 months. The move infuriated Jewish settlers, but the Palestinians dismissed the moratorium as insufficient because it allowed for the completion of about 2,500 homes already under construction and because it did not include East Jerusalem. They continue to insist on a total Israeli freeze before resuming talks.

Speaking to foreign reporters in Jerusalem last week, Mr. Netanyahu said that the Palestinian leaders had “climbed up a tree” and “they like it up there.”

Palestinian officials contend that in addition to continuing to build in the settlements, Mr. Netanyahu is trying to dictate the outcome of talks before they begin. Mr. Netanyahu has already stipulated that he will only entertain the idea of a demilitarized Palestinian state with limits on its sovereign powers.

In the session with the foreign reporters on the eve of Mr. Mitchell’s visit here, Mr. Netanyahu said that the threat of rocket smuggling into the Palestinian territories would require Israel to maintain a presence “on the eastern side of a prospective Palestinian state,” meaning along the border with Jordan.

The chief Palestinian negotiator, Saeb Erekat, responded that “the only remaining obstacle to negotiations” was “the conditions Mr. Netanyahu continues to impose.”

The Israeli demands, he added, erode “any foundation of hope for the two-state solution.”