The anti-globalisation movement just months ago seemed like yet another casualty lying in the rubble of Ground Zero. Protesters had long planned huge demonstrations for the meeting of the World Economic Forum in New York at the end of January. In practice, few people felt inclined to bring banners, shout, scream or disrupt a grieving nation. The protest fizzled out, and the whole movement seemed to have been thrown off balance.

The attack on the World Trade Center in New York initially left anti-globalisers uncertain of how to proceed. On 11 September, many activists had gathered in London and were protesting outside an arms fair. When it was announced that the World Trade Center had been hit and had collapsed, many people in the crowd cheered. To be fair, however, the gloating soon petered out when the scale of the catastrophe became clear.

The movement mutated rapidly into an anti-war coalition, with the same speakers, activists and gurus refocusing their energies on opposing America's military responses. The old themes of corporate power seemed to be quickly forgotten. Many wondered if the anti-globalisation campaigners would ever regain their old prominence.

The protests outside the recent European Union summit in Barcelona, however, showed that the movement is robust enough to survive great shifts in world opinion without losing direction. Socialist and anarchist groups claimed an attendance of half a million; the BBC, CNN and other "corporate" media estimated the number at 200,000. Either way, Barcelona looked very much like Genoa in July 2001 - and proved that 11 September had not been a deterrent to protest. Indeed, the World Social Forum in Brazil in March showed that the groups coalescing around the anti- globalisation agenda are bursting with energy and ideas.

The forum was held in Rio Grande do Sul, the only Brazilian state to hold out against the programme of neoliberalism and privatisation embraced by the rest of the country. In Rio Grande do Sul, life expectancy is five years higher than in the rest of Brazil; the illiteracy rate is 7 per cent compared to 15 per cent elsewhere in the country; and the unemployment rate is the lowest. Activists at the forum saw the crisis in Argentina as another blow against the IMF-imposed programme of neoliberalism, since Argentina had been a particularly compliant pupil of the World Bank.

Many activists began to think then that, after the blip of 11 September, world events were still moving their way. Some among them saw the need to push the movement beyond the now familiar scenes of protests and riots. They decided, in fact, to bankrupt the World Bank.

It might sound far-fetched. The bank, after all, is a huge global operation. It is owed $2.5trn by developing countries and employs 10,000 people worldwide. In 1997, it extracted $1bn more from Africa than it lent to the continent.

But who owns the World Bank? We do. Ordinary people in the west - through their trade unions, churches, town councils, universities and private investments - own the bank, but they don't know that. The bank raises nearly all its funds by issuing bonds on the private market. These are often held by socially minded institutions that would be horrified to think they were propping up an ultra-neoliberal organisation.

So activists have come up with a simple way of breaking the bank: boycott their bonds and bankrupt them.

Dennis Brutus, a patron of Jubilee 2000 South Africa and a founder member of the new campaign, has been told many times before that boycotts achieve nothing. He heard people say it when he was a prisoner on Robben Island and was pleading for the world to boycott South African goods. He is unashamed in drawing a direct parallel: "We need to break the power of the World Bank over developing countries," he explains, "as the disinvestment movement helped break the power of the apartheid regime in South Africa."

He sees the World Bank as another form of (white) colonial domination over the (predominantly black) developing world. Brutus argues that the World Bank has "denied Africa's right to health" by forcing cutbacks in spending, imposing the privatisation of healthcare and the introduction of "user fees", and even demanding that debt repayments take precedence over basic health provision. Brutus has lived to see the death of political apartheid. He now hopes to begin the fight to end what he calls "global financial apartheid".

The campaign, launched in 2000, immediately won approval from the developing world. Berta Caceres, of the Council of Indigenous People and Popular Organisations in Honduras, for example, argues that "because the impact of neoliberalism is global, we must respond at the same level. For this reason, the boycott is one of the most important tactics we Lencas [an indigenous South American people] have. We rely on the boycott to build alliances with others who are challenging the World Bank."

The campaign is starting to have some success in pressing US institutions to ditch World Bank-owned bonds. The cities of San Francisco, Boulder, Oakland and Berkeley have joined the boycott. Several US unions have also joined. Steve Stallone, communications director of the International Longshore and Warehouse Union (ILWU), says that "the World Bank growth model is based on redirecting much of a nation's wealth to transnational corporations at the expense of the vast majority of the population. It increases poverty and immiseration everywhere it goes. It is anathema to everything the ILWU stands for." It is not hard to imagine British union leaders such as John Edmonds joining in this chorus if a UK campaign gets going.

Even the little activity thus far has caused anxiety within the bank about the threat to its "AAA" bond rating. James Wolfensohn, the World Bank president, has attacked the campaign and described it as "ill-advised". British defenders of the bank - for example, the Secretary of State for International Development, Clare Short - argue that it is better to be effecting change from the inside.

Short is working within the bank's existing structures to encourage lower tariffs on goods from developing countries and to promote economic development for the world's poorest people. Brutus, however, believes that the bank is as unsalvageable as the regime of F W de Klerk, and adopts the anti-globalisation slogan attacking the Bretton Woods institutions: "Fifty years is enough."

The development of these new techniques suggests that, far from dying, the anti-globalisation movement may, in fact, be coming of age.