In theory one of the useful roles of the United Nations ought to be to focus global attention and spur action on specific issues, ranging from the alleviation of poverty to the protection of fundamental human rights.

Sometimes it has done this, as in the adoption of conventions on torture and refugees, but in recent years it has mostly tried and failed. Practical targets too often have been replaced by grandiose themes; the trend has been toward the convocation of big, expensive, windy conferences about overly broad issues, such as women's rights or social justice or "habitat", that end with vague declarations and next to no follow-up.

Until now, these meetings have been offensive mostly for their puffery, but now one approaches that threatens to do major harm to the UN as well as to the cause it claims to espouse. The grandly named World Conference Against Racism, Racial Discrimination, Xenophobia and Related Intolerance, in Durban, beginning on Friday, has highlighted one of the world's most serious and intractable problems - and through cynical and irresponsible diplomacy, threatens to make it worse.

Preparatory meetings for the conference have raised some important issues, such as the continuing discrimination by caste in south Asia and the treatment of refugees and other migrants in Europe, but no concrete change or action is likely to be endorsed.

There probably will be an extensive debate about the need for apologies and some form of restitution for slavery, but the result seems likely to be a weak general statement that will do little to resolve the issue for countries where it has importance, such as the United States. Nations happy to criticise the United States manage to shield their own records of racism from any scrutiny.

Meanwhile, if Arab and Islamic governments have their way, the final declaration will contain harsh passages that single out one country, Israel, for condemnation, label its Zionist ideology as racist, and denigrate the importance of the Holocaust.

Arab recipients of US aid, such as Egypt, have persisted in this campaign, which is itself racist, despite repeated public warnings from the Bush administration of a US boycott of Durban.

This week the State Department went halfway toward delivering on that threat, announcing that Secretary of State Colin Powell would not lead the US delegation - we think he's right not to go - and that the administration had not yet committed itself to any representation.

IT'S not hard to imagine what comes next: the Arab states insist on their reprehensible agenda, to the cost of their relations with the United States; the Bush administration boycotts the conference, triggering protests from domestic civil-rights advocates as well as foreign governments fretting about US "unilateralism"; the United Nations adopts another resolution that in effect equates Zionism with racism, reopening a debilitating wound that it thought it had closed years ago and further endangering its fragile rapprochement with the US Congress.

UN Secretary-General Kofi Annan, among others, is working hard for a better outcome. To succeed, he must ensure that Durban will be a conference about racism, not Israel.

The Bush administration could help by pledging to attend and engage with such a conference; the United States gains nothing by staging a total boycott. But no one should expect much in the way of practical benefit - not for India's lowest castes, not for immigrant workers in Saudi Arabia, not for the reputation of the United Nations.