The girl, who cannot be named as she is a minor, was caught with a recipe for explosives in her personal sketch pad, and a mobile phone containing the Anarchist Cookbook, which includes a 'how-to' manual for manufacturing explosives.

She told police the sketch pad was a school project, and the explosives recipe was in response to a children's TV show on fireworks. She denied being part of an attack plan.

However on Wednesday she pleaded guilty to two charges of possessing documents containing information likely to be of use to a person preparing or committing an act of terrorism.

The girl appeared in Manchester Youth Court in a light blue headscarf and thick jumper, accompanied by her mother.

She was arrested in Northern England on April 3, in connection with a police investigation into a 14 year-old boy who last month pleaded guilty to inciting another person to commit a terror attack on an Anzac Day parade in Melbourne.

The girl was in communication with the boy using the WhatsApp messaging application on her phone and they exchanged thousands of messages over a short period.

She commented on his plans, saying she had plans of her own. They also discussed travelling to Syria.

However there was no evidence that she was involved in, or complicit in the boy's plan.

On Wednesday judge Khalid Qureshi said he understood "the bulk of the (exchange) was fairly innocent communication".

Police also found on her phone several Islamic State publications, images and flags, and images of weapons and radical terrorist figures including Osama Bin Laden.

They also found images of a dead child, an execution and people about to be beheaded, and quotes including "I love that I should be killed in the way of Allah".

Police believed the girl had used a computer at school to search for terrorism-related material including information on IS executioner 'Jihadi John' and images of Michael Adebolajo, killer of Fusilier Lee Rigby in south London in 2013.

One image of a female child she found while searching was captioned "I will be the one who slaughters you o kuffar [infidels]; I will be a mujahid [holy warrior], insha' allah [God willing]".

Judge Qureshi said "I accept it's a unique case in its nature" but it would be treated just like other youth court cases.

He warned the girl that he had only two sentencing options under the law – either a jail sentence or a referral to a community rehabilitation program.

He asked for a pre-sentence report, including a psychological evaluation, and said he hoped the report would recommend a non-custodial sentence.

He wanted to assess how her behaviour came about and "what influences were brought to bear" on her, he said.

"The youth offending team will want to interview you and your family," he told the girl.

"It is very much in your interests you are open and honest with them about what's happened, if you are able to tell them why you got involved in what you got involved in.

"I will be asking you some questions directly about your conduct, your behaviour, why you think it has happened. I need to try to understand why this happened."

The girl was released on bail, on the condition she stay at a particular address, report regularly to police, observe a curfew and not leave the country or apply for international travel documents.

She is due to be sentenced at the Manchester Youth Court on October 15.