A United Nations inquiry today accused the Israeli military of "negligence or recklessness" in its conduct of the January war in Gaza and said the organisation should press claims for reparations for deaths and damage.

The first investigation into the three-week war by anyone other than human rights researchers and journalists held the Israeli government responsible in seven separate cases in which UN property was damaged and UN staff and other civilians were hurt or killed.

However, the UN secretary general, Ban Ki-moon, rejected the report's call for a full and impartial investigation into the war, and refused to publish the complete 184-page report. Only Ban's own summary of the report (pdf) has been released.

Israel rejected the inquiry's findings, even before the summary was released, as "tendentious" and "patently biased".

The board of inquiry, led by Ian Martin, a Briton who is a former head of Amnesty International and a former UN special envoy to East Timor and Nepal, had limited scope, looking only at cases of death, injury or damage involving UN property and staff. But its conclusions amount to a major challenge to Israel.

It found the Israeli military's actions "involved varying degrees of negligence or recklessness", and that the military took "inadequate" precautions towards UN premises. It said the deaths of civilians should be investigated under the rules of international humanitarian law.

The UN should take action "to seek accountability and pursue claims to secure reparation or reimbursement" for UN expenses and payments over deaths or injury to UN staff and damage to UN property where the responsibility lay with Israel, Hamas or any other party, the report added. In total, more than $11m worth of damage was caused to UN premises.

The inquiry looked in detail at nine incidents, in which several Palestinians died. It found the Israeli military responsible in seven cases where it had "breached the inviolability" of the UN. In one other case, Palestinian militants, probably from Hamas, were held responsible; in a final case, responsibility was unclear.

The report summary will now go to the UN security council. In a later press conference , Ban confirmed that he would be seeking no further official inquiry into the Gaza events. But he did say he would be looking for reparations from Israel on a "case-by-case" basis.

The secretary general was asked whether his decision not to publish the full report amounted to a watering down of the inquiry's findings. He categorically denied the suggestion: the inquiry was independent, and he was powerless to edit its conclusions.

Israel's foreign ministry said the Israeli military had already investigated its own conduct during the war and "proved beyond doubt" that it had not fired intentionally at UN buildings. It dismissed the UN inquiry.

"The state of Israel rejects the criticism in the committee's summary report and determines that in both spirit and language the report is tendentious, patently biased and ignores the facts presented to the committee," the foreign ministry said in a statement.

It said the inquiry had "preferred the claims of Hamas, a murderous terror organisation, and by doing so has misled the world".

The most serious incident investigated took place on 6 January, near a UN boys' preparatory school in Jabaliya that was being used as a shelter for hundreds of Palestinians who had fled their homes to escape the fighting. The Israeli military had fired several 120mm mortar rounds in the "immediate vicinity" of the school, killing between 30 and 40 Palestinians, the inquiry found.

Although Israel at the time said Hamas had fired mortars from within the school, the inquiry found this as not true: there had been no firing from within the compound and there were no explosives in the school.

It held Israel responsible for the attack and said the deaths of civilians should be "assessed in accordance with ... international humanitarian law." It also called for a formal acknowledgement from Israel that its allegations about Palestinian militants being present in the school were untrue.

The other incidents investigated were:

29 December The headquarters of the UN political mission in Gaza was damaged when Israeli air strikes hit the presidential compound next door. Staff were on site, but were protected in a bunker and not injured. The inquiry held the Israeli government responsible for the damage.

5 January An Israeli air strike hit the UN Asma elementary school in Gaza City, where hundreds more Palestinians were sheltering. The missile killed three young men who had been walking to the bathroom in the school compound. The inquiry found no weapons or ammunition were being stored in the school, and that the men had been going to the toilet and not taking part in military activity. The attack was "an egregious breach of the inviolability of the United Nations premises", the inquiry said, again holding Israel responsible for the deaths and damage.

6 January An Israeli air strike damaged the UN Bureij health centre, injuring nine people. The inquiry said the air strike had targeted and destroyed an apartment opposite the centre. It held Israel responsible for the damage to the health centre, and noted that the UN had been given no advance warning of the attack.

8 January Israeli soldiers fired at a UN convoy, damaging one of the vehicles in Ezbet Abed Rabou. The marked convoy, flying a UN flag, had been cleared by the Israeli military to travel out to pick up the dead body of a UN staff member.

15 January The UN's main headquarters in Gaza was badly damaged when it was hit by several Israeli artillery shells, including some containing white phosphorus. The shelling continued despite warnings from the UN to the Israeli military, and fires caused serious damage to the UN warehouse. Three people were injured. The inquiry held Israel responsible and said the Israeli military had a "particularly high degree of responsibility" to ensure the safety of the UN headquarters.

17 January Israeli 155mm artillery loaded with white phosphorus exploded early in the morning above the UN Beit Lahiya elementary school, where nearly 2,000 Palestinians were sheltering from the fighting. Two children, aged five and seven, were killed inside a classroom and their mother and cousin were seriously injured by shards of shell casings. Eleven others were also hurt. The inquiry held Israel responsible for the deaths, injuries and damage.

In one other case, damage worth around $29,000 was caused to a World Food Programme warehouse by a Palestinian militant group, probably Hamas. In the last case, a UN guard outside the gate of a UN girls' preparatory school in Khan Younis was killed on 29 December by shrapnel. The inquiry was unable to determine who was responsible.