Israel's recent barrage of deadly air strikes on Gaza might be war crimes, the UN rights chief said on Thursday, adding she had seen no evidence the attacked buildings were used for military purposes.

Addressing a special session of the United Nations Human Rights Council, Michelle Bachelet voiced deep concern about the surge in deadly violence between Israelis and Palestinians earlier this month.

Read: A timeline of Israel's latest military offensive in Gaza

“Although Israel undertook a number of precautions, such as advance warning of attacks in some cases, air strikes in such densely populated areas resulted in a high level of civilian fatalities and injuries, as well as the widespread destruction of civilian infrastructure,” the UN High Commissioner for Human Rights said.

“If found to be indiscriminate and disproportionate in their impact on civilians and civilian objects, such attacks may constitute war crimes.”

Before a truce took hold last Friday, Israeli air strikes and artillery fire on Gaza killed 253 Palestinians, including 66 children, and wounded more than 1,900 people in 11 days of violence, the health ministry in Gaza says.

Rocket and other fire from Gaza claimed 12 lives in Israel, including one child and an Arab-Israeli teenager, medics say. Some 357 people in Israel were wounded.

Bachelet called on “Hamas and all armed groups to refrain from use of indiscriminate rockets and mortars, for which there must be accountability”.

“There is no doubt that Israel has the right to defend its citizens and residents,” she said. “However, Palestinians have rights too. The same rights.”

The UN rights chief highlighted the scale of the destruction in Gaza.

“Although reportedly targeting members of armed groups and their military infrastructure, Israeli attacks resulted in extensive civilian deaths and injuries, as well as large-scale destruction and damage to civilian objects,” she said.

She pointed out that governmental buildings, residential homes, international humanitarian organisations, medical facilities and media offices had been hit.

“Despite Israel's claims that many of these buildings were hosting armed groups or being used for military purposes, we have not seen evidence in this regard,” she said.

The 47-member council was debating a draft resolution to launch a broad, international investigation into violations surrounding the latest Gaza violence, but also of “systematic” abuses in the Palestinian territories and inside Israel.

"Regrettably, the self-professed global champions of human rights continue to shield the occupier from global accountability, and literally provide arms and ammunitions for its widely reported war crimes and crimes of apartheid against the Palestinian people," Permanent Representative to the UN in Geneva Ambassador Khalil Hashmi said, speaking on behalf of the Organisation of Islamic Cooperation.

Meanwhile, Palestinian Foreign Minister Riyad al-Maliki said: "Israel, the occupation and apartheid authority, continues its crimes, its policies and laws to consolidate a colonial and apartheid system."

'Israeli must be held accountable'

Addressing the UNHRC special session, Foreign Minister Shah Mahmood Qureshi reiterated "the importance of the Council’s mandate to guard human rights and human dignity and the urgency to act to ensure the realisation of Palestinians' fundamental rights – right to life and right to self-determination", he said on Twitter.

He said the people of Palestine had once again faced a relentless onslaught on their rights and dignity in two weeks of "brutal Israeli aggression".

"False equivalence between the victim and the aggressor, on account of political expediency, is patently incorrect and morally reprehensible," Qureshi stressed.

The foreign minister said UNHRC "must hold Israel, the aggressor, accountable through [an] international inquiry".

He added that Pakistan supported the council’s deliberations and decisions and urged other countries to do the same.

Additional input from Reuters.