United Nations Secretary-General Antonio Guterres on Wednesday called for an end to Israeli settlements in occupied Palestinian lands.
Israel's right-wing government has in recent weeks faced criticism, including from the United States, over a decision to give retroactive permission to multiple settlement outposts in the occupied West Bank and to build new homes.
And on Monday, the UN Security Council's 15 members expressed "dismay" over the plans in a statement without binding force.
"Each new settlement is another roadblock on the path to peace," the UN chief told the body's Committee on the Exercise of the Inalienable Rights of the Palestinian People.
"All settlement activity is illegal under international law. It must stop," Guterres said, adding that "incitement to violence is a dead end. Nothing justifies terrorism."
"Our immediate priority must be to prevent further escalation, reduce tensions and restore calm," he said.
He noted, "the situation in the Occupied Palestinian Territory is at its most combustible in years."
Hours before Guterres' speech, Israeli troops killed 10 Palestinians in a raid on the occupied West Bank city of Nablus, while more than 80 people were injured, according to the Palestinian health ministry.
The Israeli military said the raid targeted militant suspects in hiding.
Palestinian envoy to the UN Riyad Mansour said the Palestinian territories are "on the verge of massive eruption."
"We will work with you Mr. Secretary-General, but we need to see action," he said.
"We are losing credibility, you are losing credibility. This fabulous system is losing credibility," Mansour said.
Monday's Security Council statement did not have the binding force of a resolution considered last week, which called for Israel to "immediately and completely cease" all settlements, but which provoked opposition from the United States, which holds veto power.
Still, Israel was quick to hit back at the declaration, with the office of Prime Minister Benjamin Netanyahu saying it denied the "historic" rights of the Jewish people.
Another 10 people were killed in an Israeli army raid in the city of Jenin last month, the deadliest West Bank operation since at least 2005.
Since the start of this year, the Israeli-Palestinian conflict has claimed the lives of 59 Palestinian adults and children, including militants and civilians.
Nine Israeli civilians, including three children, one Ukrainian civilian and a police officer have been killed over the same period, according to an AFP tally based on official sources from both sides.
Israel has occupied the Palestinian territory since the Six-Day War of 1967.
Last year was the deadliest year in the territory since the United Nations started tracking casualties in 2005.