In an op-ed in the Washington Post, Richard Goldstone, the former South African constitutional court judge and prosecutor of the International Criminal Tribunal for the Former Yugoslavia, expresses misgivings about the central finding of the UN Human Rights Council fact-finding mission report on the Gaza conflict of 2008-2009 (named, after its chairman, "the Goldstone report") that Israel's indiscriminate attacks on civilians in Gaza were intentional.

The op-ed makes strange reading.

It states that the Goldstone report would have been a different document "had I known then what I know now", but fails to disclose any information that seriously challenges the findings of the Goldstone Report.

It claims that investigations published by the Israeli military and recognised by a follow-up UN committee report chaired by Judge Mary McGowan Davis, which appeared in March, "indicate that civilians were not intentionally targeted as a matter of policy". But the McGowan Davis report contains absolutely no such "indication" and instead seriously questions Israel's investigations, finding them to be lacking in impartiality, promptness and transparency.

Goldstone expresses "confidence" that the officer responsible for perhaps the gravest atrocity of Operation Cast Lead (Israel's code name for its assault on Gaza) – the killing of 29 members of the al-Samouni family – will be punished properly by Israel, even though the McGowan Davis report provides a critical assessment of Israel's handling of the investigation into this killing.

Finally he claims that the McGowan Davis report finds that Israel has carried out investigations "to a significant degree", but in fact this report paints a very different picture of Israel's investigations of 400 incidents, which have resulted in two convictions, one for theft of a credit card, resulting in a sentence of seven months' imprisonment, and another for using a Palestinian child as a human shield, which resulted in a suspended sentence of three months.

Cold, calculated and deliberate

In short, there are no new facts that exonerate Israel and that could possibly have led Goldstone to change his mind. What made him change his mind therefore remains a closely guarded secret.

The Goldstone report was not the only fact-finding report on Operation Cast Lead. Amnesty International, Human Rights Watch and the League of Arab States (whose mission I chaired) all produced thorough reports on the conflict.

In all the reports, including the Goldstone report, there were accounts of the killings of civilians by Israel Defence Forces (IDF) in a cold, calculated and deliberate manner. But the principal accusation levelled at Israel was that during its assault on Gaza, it used force indiscriminately in densely populated areas and was reckless about the foreseeable consequences of its actions, which resulted in at least 900 civilian deaths and 5,000 wounded.

In terms of the Rome Statute of the International Criminal Court, it is a war crime to direct attack so intentionally against a civilian population (Article 8(2)(b)(i)). Such an intention need not be premeditated: it suffices if the person engaging in such action meant to cause the consequence of his action, or "is aware that it will occur in the ordinary course of events" (Article 30).

Goldstone's op-ed may be interpreted to mean that he is now satisfied (though there is no evidence to support this) that Israel did not as a matter of policy deliberately and in a premeditated manner target civilians, and that where the calculated killing of civilians occurred this was without the blessing of the Israeli military and political leadership.

But he could not possibly have meant that Israel did not "intentionally target civilians as a matter of policy" in the legal sense of intention. That Israel's assault was conducted in an indiscriminate manner with full knowledge that its consequences would be the killing and wounding of civilians is a matter of public record fully substantiated by the Goldstone report and other, equally credible findings.

In his op-ed, Goldstone declares that Hamas's indiscriminate firing of rockets into Israel, which resulted in the killing of four civilians, was an "intentional" targeting of civilians and consequently a war crime. But it is a mystery how he can suggest that the indiscriminate bombing and shooting of Palestinians in Gaza by the IDF, which resulted in nearly a thousand civilian deaths, was not "intentional".

Goldstone does not, like his critics, describe his op-ed piece as a retraction of the Goldstone report. This is not surprising. Richard Goldstone is a former judge and he knows full well that a fact-finding report by four persons, of whom he was only one, like the judgment of a court of law, cannot be changed by the subsequent reflections of a single member of the committee.

This can be done only by the full committee itself with the approval of the body that established the fact-finding mission – the UN Human Rights Council. And this is highly unlikely, in view of the fact that the three other members of the committee – Professor Christine Chinkin of the London School of Economics, Ms Hina Jilani, an advocate of the Supreme Court of Pakistan, and Colonel Desmond Travers, formerly an officer in the Irish Defence Forces – have indicated that they do not share Goldstone's misgivings about the report.

Fight for accountability . . . from Israel and Hamas

Last month the Goldstone report was referred to the General Assembly of the United Nations by the Human Rights Council with the request that it be referred by the Assembly to the Security Council, and that the Security Council submit the matter to the prosecutor of the International Criminal Court, as it has done in the cases of Darfur and Libya.

Doubtless the General Assembly will refer the report to the Security Council, despite Goldstone's op-ed, but it will end there as the customary United States veto will ensure that Israel remains unaccountable.

The Goldstone report is a historical milestone. It is a credible, reasoned, comprehensive and thoroughly researched account of atrocities – war crimes and crimes against humanity – committed by Israel in the course of Operation Cast Lead, and of war crimes committed by Hamas in the indiscriminate firing of rockets into Israel. It is a serious attempt to secure the accountability of a state that has for too long been allowed by the west to behave in a lawless manner.

That the credibility of the Goldstone report has been undermined by Goldstone's strange op-ed in the Washington Post cannot be denied.

Although the report was authored by four experts with the backing of a team from the office of the High Commissioner for Human Rights, it has undoubtedly come to be associated with the name of Richard Goldstone. Inevitably the misgivings he has expressed about his own role in the report will weaken its impact as an historical record of Operation Cast Lead.

Already, the Israeli government has expressed delight at what it construes to be a retraction of the report, and demanded both a contrite apology from Goldstone and a refutation of the report by the United Nations. Predictably the US department of state has welcomed Goldstone`s op-ed, and one fears that European governments will find in it an excuse to justify their continued support for Israel.

Richard Goldstone has devoted much of his life to the cause of accountability for international crimes. It is sad that this champion of accountability and international criminal justice should abandon the cause in such an ill-considered but nevertheless extremely harmful op-ed.

John Dugard is professor of law at the University of Pretoria, emeritus professor of the University of Leiden and former UN special rapporteur on human rights in the occupied Palestinian territory.