Only two months after the uprising that ousted President Akayev in Kyrgyzstan, Central Asia is again in turmoil. This time the situation is far more serious. Up to 500 people may have been killed and hundreds more wounded in Uzbekistan at the weekend, when troops opened fire on demonstrators attempting to storm a prison to free 23 men on trial for membership of a banned Islamic group (reports are necessarily imperfect from a country in which repression has been the rule). Thousands of Uzbeks have fled to the borders in an attempt to cross over into safety. Troops have ringed the city of Andijan, where the shootings occurred, and are on tense standby in Tashkent, the capital.

President Karimov, the former communist leader who has remained in power since the nation of 24 million became independent, is an authoritarian whose rule has become more corrupt and more dictatorial than it was in Soviet times. He has cracked down on all opposition groups, accusing even moderate Muslims of religious extremism and terrorism. He has been widely accused by human rights groups of condoning torture. And he has presided over a steady widening of the gap between a wealthy elite and the mass of ordinary Uzbeks, who say that living conditions in the past decade have worsened sharply.

The abuses in Uzbekistan are well known in Britain, partly because of the row over the dismissal of its headline-chasing former ambassador, Craig Murray, who claimed that he was silenced. Moscow and Washington are also well aware of the tensions that have been building up in the country. But, for different reasons, both have backed Mr Karimov — the Russians because they support his crackdown on all forms of Islamic opposition, which, he maintains, is linked to the violence in Chechnya; and the Americans because they established a military base there, before the intervention in Afghanistan, that plays a key role in continuing operations against al-Qaeda and Taleban supporters.

For both countries, the weekend violence presents awkward choices. President Putin, although swift to recognise the new regime in neighbouring Kyrgyzstan, is haunted by the spectre of a progressive collapse of all the post-Soviet regimes on Russia’s southern border. He has talked himself into the deluded accusation that this is being manipulated by the West, and that Russia’s interests demand firm support for existing pro-Moscow governments. America, wisely, now seems ready to speak out more forcefully, and has called on the Uzbek Government and demonstrators to exercise restraint.

There seems little hope of that. By using the threat of Islamist extremism as a cover to cow all opposition, President Karimov has alienated moderate Uzbeks and bolstered support for real extremists such as the Islamic Movement of Uzbekistan. Traditional adherents of a tolerant, moderate Islam, Uzbeks are angry at the corruption, repression and growing poverty in their country. The Government’s dreadful overreaction in opening fire on demonstrators will immeasurably boost support for radical groups across Central Asia. Neighbouring Kazakhstan and Turkmenistan, also ruled by repressive autocrats, should move swiftly to defuse tensions before violence erupts. And pressure must now be put on Mr Karimov to change course before his country and the entire unstable but strategic region are engulfed.