United Nations Secretary-General Antonio Guterres "strongly condemns" Israel's latest deadly military strikes in Gaza, his spokesman said Wednesday.
"The Secretary General strongly condemns the killings due to Israeli airstrikes of civilians in Gaza yesterday, including many children," spokesman Stephane Dujarric said.
Earlier, the UN called the deaths "appalling", as it urged all sides not to let peace "slip from our grasp".
Israel said it had carried out strikes on dozens of Hamas targets following the death of a soldier, with the Gaza Strip experiencing its deadliest night of bombing since a US-brokered truce went into effect earlier in October.
UN rights chief Volker Turk said the attacks had reportedly hit schools, homes and tents for internally displaced people within the Palestinian territory.
"Reports that over 100 Palestinians were killed overnight in a wave of Israeli airstrikes mainly on residential buildings, IDP tents and schools across the Gaza Strip, following the death of an Israeli soldier, are appalling," he said in a statement.
"The laws of war are very clear on the paramount importance of protecting civilians and civilian infrastructure."
Turk said Israel must comply with its obligations under international humanitarian law, and would be accountable for any violations.
"It is distressing that these killings occurred just as the long-suffering population of Gaza started to feel there was hope that the unrelenting barrage of violence may be at an end," he said.
Turk called for all parties in the conflict to act in good faith and implement the ceasefire, and urged other countries, particularly those with influence in the region, to do everything in their power to ensure compliance.
"The past two years have brought untold suffering and misery, and the near wholesale destruction of Gaza," he said.
"We must not allow this opportunity for peace and a path towards a more just and secure future to slip from our grasp."
