Police say an 18-year-old man arrested outside the Sydney Opera House has been charged by counterterrorism investigators with threatening to destroy property.

A police statement said on Friday the man was arrested on Thursday while wearing a backpack after the Islamic State group urged followers to stab, shoot, poison and run over Australians at iconic locations including the opera house.

He will appear in a Sydney court on Friday. He faces a potential sentence of five years in prison if convicted.

His backpack is undergoing forensic examination.