A TEENAGE girl and the East Lancashire 14-year-old boy dubbed Britain’s youngest convicted terrorist swapped more than 2,000 social media messages the day before their arrest, a court heard.

Last month, the Blackburn teenager, inspired by Islamic State (IS), who cannot be named for legal reasons, had confessed to inciting attacks on the 2015 Anzac Day Parade in Australia.

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Yesterday, a 16-year-old girl from the Longsight area of Manchester, who also can not be named for legal reasons, pleaded guilty to two offences under the Terrorism Act 2000 of possession of documents likely to be of use in preparing or committing an act of terrorism, at the city’s youth court. One of the items is said to be a recipe for explosives.

No evidence was found of the girl’s involvement in the Anzac Day plot – she had been detained alongside the Blackburn youngster in early April following raids in East Lancashire and Greater Manchester. But the pair had swapped more than 2,000 ‘WhatsApp’ messages during the day before their arrest, the court heard.

The girl had also used her school computer to research IS, the terrorist known as Jihadi John, and Michael Adebolajo, the 2013 killer of Fusilier Lee Rigby in London.

The court heard that the boy and the girl had shared more than 16,250 Whatsapp messages over an eight-day period leading up to April 3.

She had instructions on her Blackberry phone for producing a timed circuit, a DIY bomb-making document and a copy of the Anarchist Cookbook.

She also had publications by Islamic State, images of guns, knives and grenades, and photos of jihadi terror ‘heroes’. Photos of a dead child, an execution and people about to be beheaded were recovered.

Files from her school’s IT network contained searches for the Taliban, Islamic State, Jihadi John, balaclavas and Michael Adebolajo.

The Blackburn teenager has admitted inciting Australian Sevdet Besim, 18, to sabotage the Anzac Day parade and will be sentenced on September 3. The girl will be sentenced on October 15.