A London teenager was given a suspended jail sentence on Friday for his part in a "brazen" bid to steal a judge's high performance motorbike from outside court, police said.

Deon-Dre Rogers-Barrett, 19, and his accomplice, 18-year-old Shay Hollis -- as well as a third unidentified suspect -- tried to steal the BMW bike worth £15,000 ($18,400) from Snaresbrook Crown Court in northeast London.

When challenged by a security guard, Hollis threatened him with a machete but the pair then became trapped inside the grounds after security staff shut the gates, police said.

The duo dumped the motorcycle -- causing several thousand pounds worth of damage -- and fled on foot, discarding their own mopeds, helmets and the machete.

But officers from London's Metropolitan police were eventually able to trace them through one of the moped's registration as well as forensics.

Rogers-Barrett had even called the police later that day falsely claiming to have been robbed at knife point of his own moped and mobile phone.

The two teens were arrested the next month, and eventually pleaded guilty to robbery.

Rogers-Barrett was sentenced to 21 months' imprisonment suspended for 18 months and ordered to do rehabilitation activity for the attempted theft in April 2021.

Hollis was sentenced to an 18-month supervision order, ordered to carry out 12 hours of unpaid work and to pay £500 compensation to the victim.

He had previously also admitted criminal damage, threatening a person in a public place with an offensive weapon and affray charges.

"They were intent on stealing a valuable motorcycle in an attempt that can only be described as brazen and audacious," police constable Ian Croxford said in a statement.

"To ride into the grounds of a crown court and try this shows a flagrant disregard for the law."