Islam is the fastest growing religion in the UK, with up to two million followers. But its very success has brought problems. Unlike Christianity, Islam is not a hierarchical religion - there is no system of national leadership or rules. 'All mosques are equal, all Imams are independent,' explains one leading Muslim. The lack of formal structures and absence of national frameworks have caused problems, and led to flagrant abuses.

'The whole idea of the mosque is a balance between the religious authority, that is the Imam, and the administrative authority, that is the council.' However, if the Imam assumes control of the accounts or decides to give radical speeches, there is often no official body in Place to stop him. Clerics such as Abu Hamza at Finsbury Park Mosque have caused great damage to the reputation of Muslims in Britain by advocating violence against non-Muslims. But this Imam's first 'victims' were worshippers at the mosque. Taking advantage of a power vacuum, Hamza simply took physical control of Finsbury Park, leaving committee members too scared to return to their own mosque.

At another mosque in London, we see the Imam persuading worshippers to raise money to buy the freehold to the mosque's premises. The Imam himself owned the freehold, and was attempting to sell it back to his congregation at four times the price he paid for it. 'He was pulling a cover over our eyes, and our faith and our beliefs,' says one worshipper. These kind of financial abuses are particularly worrying for the community as Muslims are extremely generous in their donations to mosques.

Most sinister of all are cases of sexual assault against minors. Muslim children often attend madrassas (religious seminars) or are taught by Imams in their own home. This is Britain's biggest system of informal education, and is entirely unregulated. Trouble at the Mosque looks at three shocking cases where priests have abused children under their religious tutelage. In one of the cases, the man involved has been allowed to continue attending a mosque where children worship, even after his conviction.

This high quality and comprehensively researched investigation highlights a worrying lack of accountability at many mosques. A premonitory tale about a universal religious system wide open to abuse.

Produced by People Focus