The Syrian-born radical - known as the Tottenham Ayatollah in some newspapers - declared that the "covenant of security" under which Muslims lived peacefully in the UK had been "violated" by the anti-terrorist legislation.
"I believe the whole of Britain has become Dar ul-Harb [land of war]. In such a state," he added, "the kafir [non-believer] has no sanctity for their own life or property," he wrote on his nightly webcast, later insisting the term was merely theoretical and not meant as a call to violence.
The 46-year-old cleric, who has indefinite leave to remain in the UK, is regarded as a fringe extremist by mainstream Muslims and is banned from preaching at many mosques.
Bakri Mohammed arrived in Britain in 1986 after being expelled from Saudi Arabia for his teachings.
He set up a branch of Hizb ut-Tahrir (Party of Liberation), but departed nine years ago to form the more radical al-Muhajiroun (The Emigrants). Both groups have been accused of playing a key part in radicalising young Britons.
The organisation praised the "Magnificent 19" hijackers after the 11 September 2001 and Bakri Mohammed has been investigated by police over his allegedly inflammatory language, but no charges have ever been brought.
In November he announced al-Muhajiroun was being disbanded though successor organisations such as the Saviour Sect (Ahlul-Sunnah wal Jammah) - whose members disrupted a Muslim Council of Britain conference in April - have sprung up.
Meanwhile Hizb ut-Tahrir, which maintained a lower profile after being accused of militant recruiting at universities in the early Nineties, has sprung up again in a seemingly more respectable guise.
Its leader, Dr Imran Waheed, who is a Birmingham NHS psychiatrist who openly condemned the 7 July bombings and urged Muslims to be "decent citizens" under Islamic law, has rejected any suggestion they are extremists or violent.
The party is nevertheless banned in Germany - for being anti-Semitic - as well as other countries. Its spokesman in Denmark was found guilty of distributing racist propaganda.
Hizb ut-Tahrir is campaigning for the establishment of an Islamic state and its 3,000 members do not believe in the process of voting in the UK. Hizb ut-Tahrir proposes "carrying Islam to the rest of the world by invitation and Jihad".
It has been accused of extremism by other sections of the Muslim community, which insists it is distorting the teachings of Islam and carrying young people to more violent groups.
Pakistan's President, Pervez Musharraf, reacting to claims that some of the London bombers trained in his country, said: "There are extremist organisations in the UK - Hizb ut-Tahrir and al-Muhajiroun - who operate with full impunity ... I know that they also give sermons of hate, anger and violence. Therefore I would like to say that there is a lot to be done by Pakistan and may I suggest there is a lot to be done in England also."Reuse content