Wounded, reviled and discredited, Robert Mugabe has no intention of backing down. Taking comfort from Africa's pusillanimous refusal to deal with the dictator in its midst, the old demagogue President has returned to the tactics he knows best: denouncing a phantom enemy abroad while turning loose his party thugs to beat, shoot and intimidate his political opponents. Yesterday he emerged from the bemused silence that followed his election humiliation to harangue 15,000 cheering supporters, accusing Britain of trying to steal the election and promising to defend Zimbabwe from “imperialists” as long as he remained on Earth. Away from this stage-managed absurdity, his youthful “veterans” were breaking the bones and smashing the homes of those who had dared to vote against him.

There was, it appears, a brief moment when Mr Mugabe was ready to do a deal. Morgan Tsvagirai, the opposition leader, has revealed that he was approached by Mugabe stalwarts ready to negotiate a government of national unity in which no one would have lost jobs or faced prosecution. The move was swiftly scotched, however, by Zanu (PF) hardliners, reluctant to lose their privileges or fearful of retribution from an angry and hungry electorate. Instead, the order went out to unleash an “orgy of violence”.

Mr Mugabe has been emboldened in his defiance by the complicity of Thabo Mbeki, the South African President, who has moved from cautious neutrality to outright support for his neighbour. His bland insistence that there was no crisis in Zimbabwe - at a time when more than three million destitute Zimbabweans have fled to South Africa - defies not only logic and the evidence of a nation in freefall but also the growing impatience of the outside world.

Gordon Brown deserves full credit for voicing that impatience - in his warning to the UN. Mr Mugabe, he said, was trying to steal the election. Patient diplomacy had proved ineffective; the world, and especially Zimbabwe's neighbours, must wake up to the tragedy. Luckily not everyone in the region is blind to what is happening. South African dockers yesterday announced that they would refuse to unload a Chinese ship that arrived in Durban with three million rounds of AK47 ammunition, 1,500 rocket-propelled grenades and 3,000 mortar rounds destined for Zimbabwe. The transport union also vowed to block the movement of this military consignment to Zimbabwe, arguing correctly that it would be used only for internal repression.

This principled stand underlines the disgraceful lack of principle by the two governments on which Mr Mugabe depends: South Africa and China. Mr Mbeki's refusal to put any pressure on Mr Mugabe beyond a featherweight call for the publication of the election results is as obstinate as his denial of Aids in his own country, and appears motivated by a personal animus against Mr Tsangirai. China's willingness to continue arming the dictator is part of an overall policy of questioning neither the legitimacy nor the policies of elites in those countries whose energy and mineral wealth it seeks to buy. In both cases, this cynicism is likely to backfire: Mr Mbeki faces growing hostility at home to his hands-off approach, while China is struggling to contain global protests against its human rights policies.

This weekend there will probably be a partial recount demanded by Zanu (PF) in 23 constituencies where, in all but one, it lost to the opposition Movement for Democratic Change. Whatever the MDC challenges or court rulings, few doubt that the election commission will contrive to overturn the results and thus hand the Government a parliamentary majority. This will be the moment when the election is formally stolen. Mr Brown and other world leaders must then act. Their first step must be to demand UN moves to halt the repression that will follow as soon as Zimbabwe's police manage to acquire the weapons they seek. There is another immediate step to take: the imposition of a blanket arms embargo. It is extraordinary that this is not already in place. It is disgraceful that Zimbabwe's neighbours have not called for one. But if they are too timid to act, the UN at least must show that it cares about Zimbabwean lives.