West Australian police have uncovered ecstasy with a street value of more than $50,000 in a truck travelling from New South Wales.

Officers pulled over the truck in a routine traffic stop on Friday in Wundowie, 70 kilometres north east of Perth.

Police say the truck was travelling from Newcastle to Perth and the two men in the truck did not know there were drugs inside.

They were released without charge.

Sergeant Brendan Shanahan says 1000 ecstasy tablets were found hidden in the tyres of a child's bike.

"From the packaging I could tell that it had been altered so I extracted the bike and its parts from there," he said.

"From the bicycle there was the two tubes from the small bike quite clearly contained a hard substance so I extracted those substances and that was the ecstasy.

Sergeant Shanahan says the size of the haul suggests it is part of a large interstate drug operation.

"It wasn't a tip off, we do target our activities in relation to drug trafficking and importation and we know and realise that the trucking industry the heavy vehicle industry is a part of that."