Almost 50 kilograms of magic mushrooms worth $700,000 has been seized by police in western Sydney.

The huge haul was found after detectives attached to Cumberland Police Area Command established Strike Force Bagster to investigate the suspected manufacture of illicit drugs in the Greystanes area.

As part of their investigation, police stopped a Nissan X-Trail on Pennant Hills Road, Pennant Hills, around 12am on February 3.

During the search of the car police seized psilocybin, known as magic mushrooms, cocaine, $50,000 in cash and two knives.

The 26-year-old driver was charged and is before the courts.

Initial inquiries after the arrest led police to a home on Merrylands Road, Greystanes later that day.

It was at this residence police allegedly found the huge stash of magic mushrooms, seizing 46.3 kilograms of the drug. It has an estimated street value of $700,000.

After discovering the clandestine laboratory police went to a Silverwater facility and arrested the 26-year-old driver again before charging him with manufacturing a prohibited drug in a large commercial quantity, supply prohibited drug and organising a drug premises.

He was refused bail and is expected to appear in Parramatta Local Court on Tuesday.

Investigations are continuing.

Originally published as $700k of magic mushrooms seized in raid