The United Nations called the killings in Israel's new military strikes on Gaza "appalling", as it urged all sides not to let peace "slip from our grasp".

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 air strikes mainly on residential buildings, IDP tents and schools across Gaza, 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."

‘Distressing’

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."