A teenager who made fake bomb threats to thousands of schools across the UK, including those in Norfolk and Suffolk, has been convicted.

Norwich Evening News: An undated picture issued by the National Crime Agency of George Duke-Cohan, 19, who has admitted making bomb threats to thousands of schools Photo credit should read: National Crime Agency/PA WireAn undated picture issued by the National Crime Agency of George Duke-Cohan, 19, who has admitted making bomb threats to thousands of schools Photo credit should read: National Crime Agency/PA Wire

George Duke-Cohan triggered the evacuation of more than 400 schools when he messaged them about an explosive in March 2018.

The 19-year-old was arrested days later, but went on to send another batch of emails to schools in the US and UK while under investigation in April.

He then phoned-in a fake report that hijackers had taken over a United Airlines flight between the UK and San Francisco.

Duke-Cohan, of Mutchetts Close, Watford, pleaded guilty on Monday to three counts of making hoax bomb threats, during a hearing at Luton Magistrates' Court, the National Crime Agency (NCA) said.

His messages to schools claimed a pipe bomb had been planted on the premises.

Back in March, Norfolk police confirmed they had received 16 reports of 'malicious hoax communications' being made to schools.

He was arrested for a second time after sending further emails to schools while under investigation, but was released on pre-charge bail with conditions that he did not use electronic devices.

Before long his name was in the frame for a third hoax regarding a bogus tip-off that a flight had been targeted by hijackers.

He posed as a worried father, claiming his daughter had contacted him from the flight to say her plane had been hijacked by gunmen with a bomb.

The plane was placed on lockdown when it arrived at San Francisco airport as the report was investigated, requiring all 295 passengers to remain on board.

This caused disruption to onward journeys and financial loss to the airline, the NCA said.

A joint investigation between the NCA and the FBI was launched when a hacker group known as 'Apophis Squad' claimed on social media that it had successfully grounded flight UAL 949 on August 9.

Detectives found that Duke-Cohan had made the calls to San Francisco Airport and their police force while he was on pre-charge bail for the two previous offences.

Duke-Cohan was arrested for a third time at his home in Watford, Hertfordshire, on Friday.

He was found to be in possession of numerous electronic devices, despite the restrictions in place .

The teenager was remanded in custody after his guilty plea and is due to appear at Luton Crown Court on September 21.

NCA senior investigating officer Marc Horsfall said: 'George Duke-Cohan made a series of bomb threats that caused serious worry and inconvenience to thousands of people, not least an international airline.

'He carried out these threats hidden behind a computer screen for his own enjoyment, with no consideration for the effect he was having on others.

'Despite being arrested and having conditions imposed restricting his use of technology, he persistently broke those conditions to continue his wave of violent threats.'