A three-month-long investigation has seen one man charged with more than 300 offences related to drug supply in the Newcastle region.

Strike Force Toocooya was launched by Newcastle Police in February to investigate the supply of heroin in the area.

Following extensive inquiries, a 38-year-old man was stopped by police around 1:30 on Monday afternoon, while driving a hire car on Llewelyn Street, Merewether.

A search of the vehicle allegedly uncovered a prohibited drug believed to be heroin and cash.

Searches were then conducted at properties in Berner Street, Merewether and Park Avenue, Kotara, where officers allegedly uncovered 11-thousand-dollars worth of cash, drugs including heroin and cocaine, and a range of weapons including a replica pistol, tasers, flick knives and batons.

The man was taken to Newcastle Police Station, where he was charged with ongoing drug supply and firearm and weapon offences totalling more than 300 charges.

He was refused bail and will face Newcastle Local Court on May 22.

Image: NSW Police via