The warning from the UN envoy for the Middle East comes after the worst military flare-up between Israel and Palestinian Hamas since 2014 war. Meanwhile, a fragile calm returned to Gaza Strip on Wednesday.
The latest escalation of fighting between Israel and Palestinian Hamas has pushed Gaza to the brink of war, the United Nations envoy for the Middle East warned an emergency session of the Security Council on Wednesday.
Nickolay Mladenov delivered the stark warning as the council remained deadlocked over how to respond to the flare-up between Palestinian militants in the Gaza Strip and Israel.
"This latest round of attacks is a warning to all of how close to the brink of war we are every day," said Mladenov, who spoke via video link from Jerusalem.
The council met in emergency session at the request of the US, which had asked the top UN body to condemn rocket firings by Hamas and Islamic Jihad on Israel.
But Kuwait, a non-permanent council member that represents Arab countries, blocked the US-drafted statement, arguing that it had presented its own draft resolution that addressed the crisis.
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Serious escalation since 2014
The exchange of fire on Tuesday and into the early hours of Wednesday began after what the Israel said a barrage of rocket and mortars fired from Gaza, prompting Israel to respond with strikes on 65 militant sites in the Gaza.
Prime Minister Benjamin Netanyahu said Israel's military had delivered the "harshest blow" in years to Gaza "militants."
"Since yesterday, the army has responded forcefully to fire from the Gaza Strip with attacks against dozens of targets of terrorist organisations in the harshest blow that we have dealt them in years," Netanyahu said, according to his office.
The violence was the most serious escalation since the 2014 war between Israel and Hamas and followed weeks of Palestinian protests in which more than 100 Palestinians have been shot and killed by Israeli forces.
No Israelis have been killed.
Calm returned to Gaza on Wednesday but the UN envoy expressed concern that ongoing protests in June will lead to further violence.
"No one in Gaza can afford another war," said Mladenov.
Protection of Palestinian civilians
Kuwait is pushing for a vote at the council this week on its draft resolution calling for "the consideration of measures" for the protection of Palestinian civilians, according to the text obtained by AFP.
The US, which has veto power in the council, will oppose the measure, Israeli Ambassador Danny Danon told reporters.
US Ambassador Nikki Haley said "the people of Gaza do not need protection from an external source. The people of Gaza need protection from Hamas."
With the council deadlocked, France warned that the failure to agree on a response to the Gaza crisis was damaging to the UN.
"This increasingly heavy silence, which is becoming deafening, is not acceptable," said French Ambassador Francois Delattre.
"It is not acceptable for the Palestinian and Israeli populations, who are affected by this conflict. It is not acceptable for the world that is watching us," he said.
Early on Tuesday, some 28 mortar shells were fired toward Israel from the Gaza.
Israel said most were intercepted by its air defence systems but put residents in the area on high alert, ordering them to stay within 15 seconds of shelters.
Israel's military began air strikes soon after.
Israel's military said it hit "military targets" including a tunnel stretching into its territory, weapons stores and militant bases.
Hamas said in a statement on Tuesday that "what the resistance carried out this morning comes within the framework of the natural right to defend our people".
The military flare-up followed weeks of deadly demonstrations and clashes along the Gaza-Israel border, beginning on March 30.
The protests demanded that Palestinians who fled or were expelled in the 1948 war surrounding Israel's creation be allowed to return to their former homes, now inside Israel.
They peaked on May 14, when at least 61 Palestinians were killed in clashes as tens of thousands of Gazans protested the US transfer of its embassy in Israel to the disputed city of Jerusalem the same day.
Low-level demonstrations and clashes have continued since.
Israel says its actions are necessary to defend its borders, accusing Hamas of encouraging thousands of Palestinians to break through the border and attack Israelis.
But Israel has faced international criticism and calls for an independent investigation over its use of live fire during the protests and border clashes.