UN chief Ban Ki-moon warned Israelis and Palestinians on Tuesday they were at a "dangerous abyss" and must act quickly to calm nearly three weeks of unrest before it spirals further out of control.
The stark comments came as the UN secretary general made an unannounced visit to Jerusalem to try to ease tensions that have led to mounting international concern.
As he met Israeli Prime Minister Benjamin Netanyahu, Ban also spoke of the danger of allowing an escalation "into a religious conflict with potential regional implications" and urged efforts to ensure that did not occur.
Violent protests and a wave of Palestinian gun, knife and car-ramming attacks against Israelis have raised fears of a full-scale Palestinian uprising.
Even as Ban visited, another stabbing and a car attack occurred in the occupied West Bank, wounding three Israelis. Both alleged attackers were shot dead.
And after his remarks, Israeli troops shot dead two Palestinians in a stabbing attack on their post in Hebron in which one soldier was slightly wounded.
Fresh clashes also erupted along the Gaza Strip border, leaving one Palestinian dead from Israeli fire and five others wounded.
"My visit reflects the sense of global alarm at the dangerous escalation in violence between Israelis and Palestinians," Ban said after meeting Israeli President Reuven Rivlin.
"If we do not act fast, the dynamics on the ground will only get worse."
Ban added that "it is not too late to avoid a broader crisis" and urged renewed peace efforts, with negotiations at a standstill for more than a year.
"Beyond the immediate tensions, what is missing is the resolve to restore a political horizon for talks, and a political process that delivers real results and peace.
"We must, for the future of our children, come back from this dangerous abyss, safeguard the two-state solution, and lead people back to the road toward peace."
Ban is due to hold talks with Palestinian president Mahmud Abbas on Wednesday morning.
In a sign of growing international worry, US Secretary of State John Kerry will also meet Netanyahu in Germany this week and Abbas later at an unspecified location in the Middle East.
- Excessive force? -
More than 40 Palestinians have been killed in the upsurge in violence that began at the start of the month, including alleged attackers. Eight Israelis have died in attacks.
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Israeli security forces have found themselves seeking to clamp down on unrest while not provoking a further escalation of violence.
But checkpoints in Palestinian areas of annexed east Jerusalem, where many of the attackers have come from, and measures such as home demolitions have provoked further anger.
Videos of Israeli forces shooting dead alleged attackers that have spread online have also fed unrest, with Palestinians seeing some of the shootings as unjustified.
As he met Netanyahu, Ban warned against any misuse of force since it could "breed the very frustrations and anxieties from which violence" can erupt.
Netanyahu strongly rejected such accusations.
"Israel is acting as any democracy would to defend its citizens," he said. "We are not -- I repeat -- we are not using excessive force.
Many of the attackers have been young Palestinians who appear to be acting on their own, making it difficult for security forces to prevent the violence.
Netanyahu dismissed arguments that frustration over the occupation and Jewish settlements was driving the attacks.
"I believe it is time to tell the truth about the causes of Palestinian terrorism," he said ahead of his meeting with Ban.
"It is not the settlements, it is not the peace process, it is the desire to destroy the state of Israel pure and simple."
Ban acknowledged both Palestinian frustration and Israelis' fear in the face of violence.
He said he was "deeply troubled by statements from Palestinian militant groups including Hamas and Islamic Jihad praising such heinous attacks."
Some politicians have urged residents to arm themselves, and rights activists blamed such comments in part for an incident on Sunday night, when an Eritrean man was mistaken for an attacker and killed.
The mob violence came after an Arab Israeli gunman also armed with a knife stormed a bus station in the southern Israeli city of Beersheba, shooting dead a 19-year-old soldier and wounding around 10 others.
The gunman was killed, while a security guard at the bus station shot the 29-year-old Eritrean thinking he was a second attacker. A mob also beat him, and the man died later.
Netanyahu warned Israelis against vigilantism after the incident, saying no one should "take the law into their own hands".