Police are working to safely dispose of what they believe is an improvised explosive device (IED) in Blenheim.
The suspected bomb was found when police raided a property on Tuesday morning.
"NZDF personnel will be working to safely remove and dispose of the item this afternoon," a police spokesperson said.
Also found was a firearm and a quantity of methamphetamine.
Police said the items were discovered when they executed a pre-planned search warrant on the property.
A 22-year-old man appeared in Blenheim District Court on Tuesday charged with a number of drug-related offences.
He was released on bail and will next appear in court on September 30.