As Pope Benedict flies to the Holy Land, an unholy row has broken out over allegations that Israeli forces deliberately or recklessly fired on United Nations personnel and property in Gaza during January's military action against Hamas, killing staff and civilians sheltering there. The terms of this quarrel are wearily familiar. As has happened before, most notably during action against Hezbollah in Lebanon in 2006, international allegations that Israel has wrongly conducted itself are dismissed by Israeli spokesmen. There is a strong implication that the allegations are biased, concocted by Israel's enemies, and believed only by those - too numerous to mention - who are tainted by anti-Semitism. Opinion inside Israel, and to a considerable extent Jewish opinion worldwide, continues to believe that Israeli armed forces behave little short of impeccably, under extreme provocation. Meanwhile opinion outside Israel, and among non-Jews, tends to harden the other way. This is a propaganda war Israel seems destined to lose, a loss that it has already discounted in advance. But must it be so?

The international outcry against Israel was not confined to alleged attacks on UN property, but covered all aspects of Israeli military activity against Hamas. A large proportion of the Palestinian casualties were apparently civilians. But Hamas militia often dress as civilians, do use women operatives and even children, and do sometimes deliberately mount their attacks from civilian areas. The illegality of the action of Hamas itself, including its rocket attacks on innocent Israeli citizens, is manifest. But the world expects better of Israel, a democratic country with civilised Western values. In this case, the circumstances involving UN property were more specific, and lent themselves to a more detailed and impartial investigation. The UN Security Council duly commissioned one: it found many of the allegations proved. But the Israeli Government promptly and predictably rejected those findings as biased and tendentious. The Israeli Defence Forces had already carried out their own inquiries and found the charges baseless, it said.

Because of the weight of international prejudice against it, Israel clearly does not expect its denials to be believed. But this is becoming a self-fulfilling prophecy: any organisation that announces itself to be blameless on the basis of its own inquiries is facing a credibility gap of insurmountable proportions. The Metropolitan Police in London, for instance, have learned the hard way that declaring themselves innocent of all wrongdoing on the basis of their own internal inquiries invariably fails to satisfy a sceptical British public, which would prefer, nevertheless, to believe the police are well behaved. The public is all too aware of the tendency of institutions to close ranks in the face of hostile criticism.

Israel has many friends in the world who would be appalled to see themselves accused of anti-Semitism. But they are finding the price of that friendship is becoming too high, if it means having to believe every word uttered by an Israeli Defence Forces spokesman dismissing well-attested findings of an independent international inquiry (with which it had, incidentally, cooperated). Israel has a moral duty to its friends to neither corner them into defending the indefensible nor force them to live with a bad conscience. A more nuanced and realistic reply to the UN would have been better policy, and more honest.