Christchurch police warn a rise in synthetic cannabis across the city, poses a risk to businesses

Three men were arrested after 200-thousand-dollars worth of synthetic cannabis, cash, ammunition and a firearm were seized yesterday.

Police say synthetic cannabis is the most lethal form of illicit substances in New Zealand in recent years, implicated in at least 70 deaths.

Detective Sergeant Brad Grainger says the significant increase in its supply has affected retail offending and disorderly behaviour.

The three men - aged from 44 to 52 - face a variety of charges