DRUG detection officers were surprised to discover a man carrying a stash of silver bullion instead of mind-altering substances when they stopped him on a NSW train line.

Police are seeking the owners of the silver bars and coins after investigations revealed the man couldn't prove he owned them.

Officers involved in a drug detection operation made the discovery after stopping the 34-year-old at Broadmeadow railway station in Newcastle in July.

He was found to be carrying five kilograms of silver bullion including three one kilogram silver bars, two one kilogram silver coins and 75 smaller silver coins worth of about $6000, police said.

He has been issued with a court attendance notice for goods in custody and will appear in Newcastle Local Court on October 8.