Hizb Ut-Tahrir.

Thousands of HuT members have been arrested in Pakistan, Afghanistan and the former Soviet republics of Central Asia in the past two years. Like the Neo-Salafis, HuT calls for a single Caliphate to rule over the Muslim world - by implication over the whole world. HuT has branches throughout Europe and Central Asia. It is active in the multi-ethnic Fergana Valley, which spills across the borders of Uzbekistan, Tajikistan, and Kyrgyzstan.

HuT (party of liberation) rooted in Uzbekistan is spreading in Central Asia, where poverty, weak government, and many jobless males have created a perfect storm for Islamists. HuT works with al-Qaeda, which mediates between its predominantly Uzbek fighters and the Taliban. HuT uses drug money to spread around the world. Drug lords and HuT share hostility to state authority. HuT's overriding objective is to unite the Muslim world under a single caliph, or supreme theocrat, reviving a system which collapsed with the demise of the Ottoman Empire early in the 20th century. HuT freely operates in Europe, with its largest membership in Britain. HuT is the base from which Muslim doctors have emerged as would-be suicide bombers.

Bilal Abdullah, an Iraqi doctor, on July 6 became the first person to be charged over the car bomb attacks on London and Glasgow. Dr Abdullah, arrested after a flaming Jeep was driven into the arrivals hall of Glasgow Airport on June 30, was charged with conspiring to cause explosions. He was working at the Royal Alexandra Hospital in Paisley, Scotland, before his arrest. He was transferred to London's Paddington Green police station after his arrest and charged on advice from the Crown Prosecution Service. Seven people have been arrested in the UK over the plot, including a second man at Glasgow Airport who is being treated for burns.

In Australia police last week stepped up investigations into links between the attacks in the UK and a number of Australia-based doctors. Raids by Australian police on July 6 followed a July 2 arrest at Brisbane airport of Muhammad Haneef, an Indian doctor, as he was trying to leave the country. Dr Haneef is believed to be related to Sabeel Ahmed and Kafeel Ahmed, two of the seven people detained in the UK. Dr Haneef had yet to be charged but had his detention order extended for the third time.

The charge against Dr Abdullah heightened attention on security in London as the capital prepared to commemorate the second anniversary of the 7/7 bombings and for an influx of visitors attending the first stage of the Tour de France and the Live Earth concert. The commemoration of the bombings was more low-key than last year. The main ceremony was a wreath-laying at King's Cross at 8.50 am, the time of the first explosion, led by new PM Gordon Brown.