BRITAIN'S youngest terrorist, who plotted to murder police officers in Australia, has taken his bid for lifelong anonymity to the High Court.

The teenager, from Blackburn, sent encrypted messages instructing an Australian jihadist to launch attacks during a 2015 Anzac Day parade.

Then aged just 14, he took on the role of "organiser and adviser" and suggested beheading or using a car to kill officers.

He was jailed for life at Manchester Crown Court in October 2015 after he admitted inciting terrorism overseas.

Now 18, he is seeking an order to keep his identity secret for the rest of his life.

A ban on identifying the teenager made at the time he was sentenced would normally expire upon him turning 18.

But he is asking the High Court in London to grant an injunction which would prevent him from being named - a rare step only taken in a small number of cases.

The youth's lawyers told the court there is a "significant risk of attacks or retaliation against him" if his identity is made public.

They also said he would be at risk of "re-radicalisation" by extremists and that his relatives would be likely to face reprisals were he named.

Edward Fitzgerald QC, representing the teenager, said: "There is the risk of violent attack, the risk of re-radicalisation and the risk to his rehabilitation and current progress, as well as the risk to his family.

"We say all those factors together justify preventing the disclosure of the fact that the person bearing his name was responsible for the incitement when he was 14."

Mr Fitzgerald said there have been "persistent and serious" threats made online to harm or kill the teenager.

A number of media organisations have made representations to the court, arguing that he should be named.

An interim injunction preventing his identification was made pending the outcome of the hearing.

Only a handful of lifelong anonymity orders have been made to date, including those granted to Jon Venables and Robert Thompson, who murdered Liverpool toddler James Bulger, and child killer Mary Bell.

A challenge by James Bulger's father and uncle against the lifelong anonymity granted to Venables is due to be heard at the High Court next month.

The teenager was recruited online by Islamic State propagandist Abu Khaled al-Cambodi.

Over nine days in 2015, he sent thousands of messages to 18-year-old Sevdet Besim, instructing him to kill police officers at the remembrance parade in Melbourne.

Australian police were alerted to the plot after British officers discovered material on the teenager's phone.

Anzac Day is held on April 25 each year to commemorate Australians and New Zealanders killed in conflict and, in 2015, marked the centenary of the First World War battle in Gallipoli.