Man in custody after police helicopter search near Devonport

A man allegedly linked to a series of incidents in Tasmania's north-west, including a service station robbery, is in police custody following a multi-hour search.

Police said they were first notified about the man shortly after 9am on Sunday, when they received reports he was "acting erratically" on Macfie Street in Devonport.

They said members of the public reported he was "knocking on doors and demanding keys to their vehicles" before he left the scene in a white Toyota.

Police said a service station in Railton, about 22 kilometres south of Devonport, was robbed just before 10am, with a quantity of cash taken from the premises.

The man is then alleged to have stolen a silver Alfa Romeo from Kimberley, about 9 kilometres south-east of Railton.

Police resources, including a helicopter, were deployed to search for the man and the stolen vehicle.

The suspect was described as being about 5 feet 8 inches in height, with short hair, olive complexion and facial tattoos.

Police said the man was then detected in the Penguin area, about 30 kilometres west of Devonport, just before 5pm following information from the public.

They said he fled from the Alfa Romeo near Preservation Bay, and attempted to escape on foot before surrendering to police and being taken into custody.

Investigations into the incidents are continuing.