The man was arrested under the Terrorism Act and taken into custody (Representational)
An 18-year-old youth was arrested on Friday by London's Metropolitan Police on suspicion of planning terrorist acts, Scotland Yard said in a statement.
The detainee, whose name and nationality were not made public, was arrested on a street in north London by armed officers, Efe news reported.
"The man was arrested under the Terrorism Act and taken into custody at a south London police station," said the Met police in a statement.
According to the interior security agency MI5, the current terror threat level in the UK is severe, meaning an attack is highly likely.