Is it a real revolution in Tunisia or will another member of the ruling elite replace President Zine el-Abidine Ben Ali who took flight on Friday? It is a crucial question for Arab world, where other corrupt police states face the same political, social and economic problems as Tunisia.

A striking feature of the Middle East for more than 30 years has been the unpopularity of the regimes combined with their depressing ability to stay in power. Most have found ways of preventing revolutions or coup d'etats through ferocious security services protecting rickety state machines that mainly function as a source of jobs and patronage.

In Tunisia, Ben Ali, along with other Arab leaders, presented himself as an opponent of Muslim fundamentalism and therefore won tolerance if not plaudits in Western capitals.

But the revolution that is brewing across the Middle East is of a traditional model springing from high unemployment, particularly among better-educated young men, and a ruling class unable to resolve any of their countries' economic problems. The most obvious parallel with Tunisia is Egypt, where the sclerotic regime of President Hosni Mubarak clings to power.

Will the present so-called "soft coup" work, whereby prime minister Mohamed Ghannouchi takes power and calms down protesters by promises of reform and elections? It does not look very likely. The declared state of emergency is not working. There is no reason to suppose a political leader so closely associated with the old regime will have any credibility with people in the streets.

There is plenty in common between the situation in Tunisia and that in Algeria, Jordan and Egypt. Economic and political stagnation is decades old. In some states it is made more tolerable by access to oil revenues, but even this is not enough to provide jobs for educated youths who see their path blocked by a corrupt elite.

There are echoes of the Tunisian crisis in other countries. In Jordan the security forces have been battling rioters in Maan, a traditional site of unrest where the government has difficulty coping. In Kuwait there was an attack by security forces in December on academics and members of parliament. Food prices have been going up.

Yet all these regimes that are now in trouble had a carefully cultivated image in the west of being "moderate" and anti-fundamentalist. After the invasion of Iraq, US president George Bush and British prime minister Tony Blair made much of their democratic agenda for the Middle East, but when one of the few democratic elections to take place in the region produced victory for Hamas among the Palestinians of Gaza and the West Bank, the US did everything to thwart the outcome of the poll.

The Middle East still has a reputation for coups but a striking feature of the region since the early 1970s is how few of the regimes have changed. The forces behind the Tunisian events are not radically new but they are all the more potent for being so long suppressed.