The man, who lives in Oslo and is in his thirties, was arrested last weekend. He is reported to have made 'Islamist-motivated' threats against media organisations and individuals, broadcaster NRK reports.
He will appear at Oslo City Court on Tuesday with regard to preliminary detention.
Although PST's senior advisor Martin Bernsen declined to comment on whether the man was previously known to the security agency, he does not have any prior convictions.
Bernsen said that PST became involved in the case due to the nature of the threats and who they were made by.
“PST arrested the man with the assistance of an emergency response unit. We took over the investigation after an overall assessment,” he told NRK.
Threats were made against several individuals by the man, he added.
“Several threats against several persons and institutions will be dealt with in the district court today,” he said.
The man will be charged with breaching paragraph 117 of Norway's criminal law, which relates to “interfering with the operations of important societal institutions, such as for example a public authority, political party or media organisation” through “the use of force, violence or threats, or in other illegal and organised ways”.
Up to six years imprisonment can be given under Norwegian law for crimes of this type.
Mette Yvonne Larsen, the man's defence lawyer, told NRK she did not wish to comment.