Kofi Annan has rarely been blunter, more heartfelt or more anguished in his appeal. Kenya, he told its leaders yesterday, was in turmoil, its people suffering, its land untilled, its tranquillity rapidly descending into chaos. The former United Nations Secretary-General knows that he is racing against time in his desperate attempt to halt the downward spiral. No one, he said, could stand by and allow the violence and the killings to go unchecked. Kenya's leaders had to lead, to take charge and to act with urgency.

What he and the world have seen is the terrible example of what happened before, just across Kenya's borders. At the beginning of April 1994, Rwanda similarly stood at the abyss. Gangs of youths, armed with clubs and machetes, roamed the streets. Families were slaughtered in the streets, burnt alive in churches and refuges, hunted down and clubbed to death. French, Belgian and US troops tried, feebly, to intervene but were overwhelmed. In hindsight, Mr Annan and the UN realised that they failed to heed the alarm from Kigali. The did too little, too late.

The killings in Kenya have gone rapidly beyond the bitterness of a stolen election. Ancient tribal animosities, stirred by feuding politicians, have revived historic arguments over land and grazing rights, inflamed the loathing among the rural poor for the corrupt elites, shattered the tolerance engendered by prosperity and stability and again set Kikuyus against Luos, Kalenjins and others who resent the dominant tribe and voted for Raila Odinga, the defeated presidential candidate. Kenya does not have the bloody history of Hutu and Tutsi hatred; but in too many chilling ways the descent into violence is as rapid and random as the apocalypse in Rwanda.

Mr Annan's warnings are addressed as much to the outside world as they are to President Kibaki and Mr Odinga. They could not be more urgent. Paralysed by indecision and conflicting interests, Western leaders have done little except urge restraint, hint at a suspension of aid and draw up plans to evacuate their nationals. It is time that George Bush, Gordon Brown and European leaders were more outspoken in their demands, robust in their diplomacy and forthright in their denunciations of the terrible events threatening to ruin not only Kenya but also, by that example, democracy and prosperity in much of Africa.

Insisting on a rerun of the disputed election may be a moral imperative. Mr Kibaki's mendacious audacity must not be allowed to succeed. If the West, for reasons of political convenience, were to accept his fraud, the despair of those battling corruption everywhere would poison hopes of rooting democracy more firmly in Africa. But the return to the ballot box is not the immediate priority. There is almost no chance that a free vote could be held while politicians are murdered, marauding gangs lurk with their machetes and resurgent criminals pose as vigilantes of their tribes. First, therefore, Kenya's politicians must unite to halt violence by a government of national unity, however painful the step to those who feel cheated. Then they must police whatever truces can be arranged, with national troops or those from outside. The UN and the European Union must be ready to back peace with muscle. Political legitimacy can only be settled within Kenya. Luckily, the country's Parliament still commands some authority and respect. It is time for its members to set aside factional or tribal loyalties and to enforce a political stand-off that might, just, halt their country at the abyss.