An elderly Melbourne couple has unwittingly become the recipient of a huge haul of drugs after mistakenly signing for a parcel containing $10 million worth of methamphetamines.

Key points: The couple called the police after opening the package

The couple called the police after opening the package Police allege it contained 20 kilograms of methamphetamines

Police allege it contained 20 kilograms of methamphetamines A 30-year-old man has been charged with importing a commercial quantity of drugs

The couple received an unexpected surprise when a package, containing bags of white powder, was incorrectly delivered to their home near Werribee in the city's west.

Police allege the bags contained around 20 kilograms of methylamphetamine, known by the street names meth and ice.

The pair called the police shortly after making the discovery.

"The occupants of the premises are obviously quite elderly, so they're unsure of the significance of the find," Detective Acting Senior Sergeant Matthew Kershaw said.

"Obviously in terms of what we have recovered, we know it's quite significant. But we're just assuring them that they've done absolutely nothing wrong."

Police allege the package contained around $10 million worth of the drug.

Detectives later executed a search warrant at a house in Bundoora, where another 20kg of amphetamine was found.

Zhiling Ma, 30, from Bundoora was arrested at the scene, and later charged with importing a commercial quantity of amphetamine.

He made no application for bail and will return to court on July 29.

All up, the 40kg of drugs are estimated to be worth around $20 million on the streets.

"It's quite a large find … that's 800,000 hits off the street that we've intercepted," Acting Senior Sergeant Kershaw said.

Police said the investigation was still ongoing and would involve the drug taskforce.