Two objects seized in early March from a 21-year-old man arrested on suspicion of making bomb threats were determined not to have been explosives, police in the Swiss capital Bern said on Thursday.

The man, who police have said is from Afghanistan, remains in investigative custody and is undergoing a psychiatric evaluation, a spokesman for the Bern cantonal police said.

"Tests conducted by an external laboratory found no explosion or fire danger," the spokesman said.

Authorities in the March 2 incident initially used equipment from their explosives unit to disarm the objects, which police said were wrapped in wire and viewed as suspicious.

The area around the Heiliggeistkirche, or Church of the Holy Ghost, near the Bern train station, was temporarily closed for security reasons and transport re-routed during the incident.