The presidents of six countries stretching from Beijing to the Caspian Sea are meeting in Uzbekistan today to discuss their shared security concerns. The six, known as the Shanghai Co-operation Organisation, are China, Russia and four Central Asian states. Afghanistan and Mongolia will attend as guests. The focus of the summit will be the opening of a special centre set up to combat what the government has called terrorist groups. Armed police have been out on the streets of Tashkent since dawn, creating, they hope, a safe corridor for the presidents to travel into the city centre. They have blocked the main roads with army trucks and the city is at a virtual standstill. These extreme measures reflect the theme of the summit - the security of this wide range of nations spanning most of Asia. The Chinese have coined a special catchphrase: we must combat, they say, the three evils of terrorism, extremism and separatism. China\'s main concern is the Muslim Uighur people of Xinjiang in western China, many of whom resent the rule of Beijing, while the Uzbek authorities pitch their struggle against the anti-government Islamic movement and the Russians against some Chechen groups. The summit will project all these and other dissenting peoples as somehow laced together, aspects to a global problem. To voice their common purpose, the Shanghai group is to open what it calls an anti-terrorism centre in Tashkent, where the various security forces will share information and strategies. But there are worries that some of the dissident voices have legitimate points of view that are being suppressed by powerful governments. There have been mass trials and executions of Uighur activists in China and human rights groups estimate that Uzbek jails contain perhaps 7,000 political prisoners. Police swept away a tiny demonstration against the summit. The protestors were trying to make the point that very few people in the Shanghai bloc have freedom of speech and assembly. (BBC)