French spies planned to assassinate the extremist preacher Abu Hamza on a London street after they grew frustrated with Britain’s failure to deal with him, it has been claimed.

According to a major investigation by the organisation HOPE Not Hate, French intelligence services dubbed the UK capital “Londonistan” because of a growing reputation for harbouring Europe’s Muslim fundamentalists.

Seeking to take advantage of the fear surrounding the London nail bombings by the neo-Nazi militant Davud Copeland, security officials from Britain’s European neighbour hatched a plot to kill the cleric and blame it on the far-right extremist group Combat 18.

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Spies got as far as identifying the weapons they would use to mimic those favoured by the organisation, and would have sent Hamza faked death threats pretending to be from the group. It is not clear why the plans were not carried out.

In a completely separate earlier plot, the French spying network Direction Générale de la Sécurité Extérieure (DGSE) contemplated kidnapping Hamza from his West London home, putting him in a ferry and moving him to France.

Those plans came amid fears that Algerian terrorists were going to target the 1998 football World Cup in France.

Reports of the two plots come from the extensive investigation entitled “Gateway to Terror” and published today by the HOPE Not Hate group. It looks into the influence of the now-banned al-Muhajiroun group and its links to Hamza and the British Islamic preacher Anjem Choudary.

Lead author Nick Lowles wrote: “One plot hatched by French intelligence that has, until now, not previously come to light, was the idea of assassinating Abu Hamza in London.

“The plan was to impersonate the British Nazi group Combat 18 and then allow them to take the blame.

“In the immediate aftermath of the London nailbombings, the French considered sending death threats in the style of C18 and then killing him with the same type of weaponry that the group was thought to possess.

“However, as with the kidnap plan, the assassination attempt was aborted and it is unclear how advanced the planning of either idea progressed.”

Hamza preached at the Finsbury Park mosque in north London for years until he was jailed in 2006 for inciting murder and racial hatred. He was finally extradited to America last year to face terrorism charges.