Leading Article: A challenge to Mr Lula

They are known as the Bric countries in current marketing jargon: Brazil, Russia, India and China - the fast-growing almost-developed countries that are destined to inherit the Earth. By 2050 they will account for 40 per cent of the world's population and are predicted to be the world's dominant economies.

Of the four, Brazil is often regarded as the most promising. Russia has its impending demographic crisis and stuttering democracy. India is held back by the caste system that keeps poverty in place and China by the unevenness of its development and proliferating social unrest.

Brazil, though, seemed to have almost everything going for it. Economic reforms in the Nineties had brought stability compared to the lurching from boom to bust that had gone before. The landslide election of President Lula in 2002 was a vindication of Brazil's democracy and gave hope to the country's poor. And, rather than destabilising the country with a headlong rush to radical reform, Mr Lula wisely gravitated towards the centre, promising sound stewardship of the economy.

If the events of recent days in Sao Paolo are at all a harbinger of things to come, however, some of the optimism may have to be trimmed. More than 70 people, most of them police officers, have been killed in more than 100 assaults on police stations and orchestrated riots in prisons. Initially, the attacks were dismissed as the work of criminal gangs, infuriated by the dispersal of prisoners to more remote, high-security, facilities. As the days passed without respite, however, it was hard not to see the violence in a political light. In scale, ferocity and choice of targets, these co-ordinated assaults presented a direct challenge to the authority of the state.

No modern state is worth the name if it can be held to ransom by individuals or groups who operate outside the law. But President Lula was partly right when he put the violence down, ultimately, to Brazil's yawning wealth gap and the lack of investment in education. These, though, are scourges that can only be tackled in the long term. In the meantime, he may find himself increasingly trapped by reforms that go too slowly for the poor and too fast for the rich, including the gangs that feed off their money.