A British teenager incited a man in Melbourne to break into someone’s home and “get your first taste of beheading”, a London court has been told.

The 15-year-old, who cannot be named for legal reasons, pleaded guilty at the Old Bailey on Thursday to inciting the Melbourne man to murder police officers in a terror attack at an Anzac Day parade in Melbourne this year.

The teen, who remains in a youth detention centre, appeared by video link from Manchester.

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Wearing glasses, a grey shirt and a dark tie, he sat quietly during the hearing in front of Justice John Saunders, saying only the word “guilty” when asked to plead.

The prosecution dropped a second charge of inciting a terror act, namely the “murder by beheading of a person in Australia”.

Prosecutor Paul Greaney QC told the court the intentions of the plotters and their targets were revealed when investigators discovered thousands of electronic messages between the boy and a man in Australia.

The court heard they both supported the Islamic State group.

Mr Greaney said a March 18 message from the boy, who was 14 at the time, contained the suggestion “you break into someone’s home and get your first taste of beheading”, prompting the response, “it seems a little risky”.

Mr Greaney said that though the specific charge of inciting a terror act to behead someone had been deleted by the prosecution, the incitement to behead would still be canvassed under the remaining charge.

Following the arrest of the boy, police made arrests in Australia and two men face charges over the alleged plot in a Melbourne court.

Justice Saunders on Wednesday ordered pre-sentence and psychiatric reports on the teen and asked that particular attention be given to whether there had been any indoctrination and what measures could be taken to reverse that process.

He adjourned the matter for sentencing before him on September 3 in the Manchester Crown Court.

-AAP