Alleged armed man arrested boarding ferry

A man has been charged after allegedly carrying weapons onto a Bass Strait ferry.

The 20-year-old South Australian man was the target of a vehicle search on Tuesday night as he boarded the Spirit of Tasmania at Devonport.

Detective Inspector Robert Gunton said the man's nervousness drew police attention.

Police and port security say they found parts of a homemade replica firearm, which was not capable of being fired.

Ammunition and five knives were also allegedly found in the car.

The incident comes less than a fortnight after police stepped up security checks at ports following Australia's heightened terrorism alert level.

However, Tasmanian Premier Will Hodgman said on Wednesday he was advised the incident was not terrorism-related.

The man has been charged with three firearm offences plus possessing a dangerous object in a public place.

He will appear in court at a date to be confirmed.