A 19-year-old has admitted making bomb threats to thousands of schools that led to more than 400 of them being evacuated.

George Duke-Cohan from Watford also sent mass emails to schools in the UK and US claiming pipe bombs were planted on their premises while he was under investigation.

At Luton Magistrates' Court yesterday he admitted making bomb threats to thousands of schools and a United Airlines flight travelling from the UK to San Francisco last month.

He was arrested in his bedroom at his family home in Watford.

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This is the moment George Duke-Cohan was arrested for the third time after making hoax calls and saying an aircraft had been taken over by gunmen

Audio released today features George Duke-Cohan posing as a concerned father whose daughter has told him her flight was hijacked by gunmen, one of whom has a bomb.

He can be heard complaining as he feigns frustration at not being given an update on the supposed hijacking.

The teenager, from Hertfordshire, pleaded guilty to three counts of hoax bomb threats.

Duke-Cohan (pictured) made hoax threats while under investigation for another set of bomb threats

Hundreds of UK schools were evacuated following threats in March, with Duke-Cohan arrested days after the mass hoax.

But while under investigation in April, he claimed bombs has been placed at both American and British schools.

The fake bomb threats were revealed at the time to be part of a Minecraft gamer feud.

Threatening emails were spoofed to look like they had been sent by a gaming network known as VeltPvP - a Minecraft player-versus-player server.

Up to 24,000 emails were sent to schools across the UK, including in the North East, London, Bristol and Humberside.

While on bail for threats made to schools, Duke-Cohan phoned San Francisco Airport and their police officers to claim an explosive was on board.

Hacker group the Apophis Squad claimed flight UAL 949 was grounded due to their actions in a post on Twitter in August.

Duke-Cohan pretended to be a worried father when he rang the airport, claiming his daughter was on board the flight.

He told staff that his daughter had contacted him to say gunmen had hijacked the aircraft and that one had a bomb.

Bishopsalt School in Uxbridge was one of the 400 that was evacuated due to the bomb hoaxes this year

Selly Park Technology College for Girls in Birmingham (pictured) was one of the 400 schools evacuated after receiving a threat

Fairholme Primary School in Feltham, west London, told parents they would be closed due to the threat earlier this year

Walsall College (pictured) was also evacuated as a result of the bomb hoaxes earlier this year

Duke-Cohan was arrested for a third time at his home in Watford (pictured) following the mass bomb hoax

Once it landed in San Francisco, the plane was quarantined as security operatives descended and the 295 passengers were told to remain on board.

The investigation grounded the aircraft, disrupting other scheduled flights at the airport.

Feud that sparked hoax A row between Minecraft gamers is thought to have sparked thousands of bomb hoax emails. The threats were mocked up to look as though the gaming network VeltPvP had sent them. The sender hoped to get the domain suspended for abuse in a bid to discredit the network. VeltPvP allows Minecraft players to go head-to-head using their server. At the time, Sky News reported the hoaxer's accusation that the network was engaged in a campaign of shutting down rival Minecraft servers. Advertisement

The National Crime Agency (NCA) arrested Duke-Cohan for the third time in his bedroom on August 31.

He was detained at his parents' home in a suburban street where property prices range from about £350,000 to £400,000, according Right Move.

Officers recovered electronic devices belonging to him, the use of which was in contravention of the pre-charge bail conditions imposed on him.

He has been remanded in custody and is set to appear for sentencing at Luton Crown Court on 21 September.

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.

'Law enforcement take such offences extremely seriously. This investigation proves that operating online does not offer offenders anonymity. We will identify you and you will be brought before the courts.'