Part of the shared pathway next to the Whanganui River near the City Bridge has been cordoned off following a fire around 5.27am on Wednesday.
A Fire and Emergency (FENZ) spokesperson said two appliances responded to the incident.
“It’s gone through three to four planks, causing holes in the walkway adjacent to the arcade.
“With it being suspicious, we have handed it over to police as well.”
A police spokesperson said they received a wilful damage report at 5.40am and the Whanganui District Council was advised of the incident.