Staff at Hawke's Bay Prison said its trained drug detecting dog, Narco, smelled the cannabis in a parcel addressed to a prisoner during a mail check last week, the Wellington Dominion Post reported Wednesday.

Prison manager George Massingham said 20 grams of cannabis was hidden inside the glove, which had been plastered in food spread marmite and shoved inside a running shoe.

"Our drug dogs are trained to detect certain odors down to parts per trillion, so it takes more than sandwich spread, however strong-smelling, to fool them," Massingham said.

Massingham said the sender's details have been forwarded to police.

Copyright 2009 by United Press International.