According to a police statement on Wednesday, at around 9.10pm on Tuesday evening police were notified that an armed man had left a backpack at the Cafe Fédéral on Bärenplatz in the centre of the Swiss capital.
Witnesses said the man made threats against the public and then headed in the direction of the Bundesplatz, where the Swiss federal parliament building is located.
Police were able to find the man a few minutes later and arrested him.
For security reasons, the Bundesplatz, parts of the Bärenplatz and surrounding streets were blocked off by police before a robot device was sent in to secure the backpack.
It was finally removed from the scene and taken for further investigation.
The police cordon was removed just after midnight.
Police have given no further details about the contents of the backpack, nor have they confirmed reports that the man was indeed armed.
Anyone who saw or heard the man at the Cafe or in the Bundesplatz should call police on 031 634 41 11.