A man has been charged after $5.2 million worth of illegal drugs were seized from a large clandestine laboratory in Sydney's south-west.

Drugs with an estimated street value of $5.2 million were uncovered in a raid on a rural property in Calf Farm Road at Mt Hunter, west of Camden, on October 24.

A man has been charged after $5.2 million worth of illegal drugs were seized from a large clandestine laboratory in Sydney's southwest. (NSW Police)

Among the 450 items seized were more than 21kg of MDMA powder and pills, 28 litres of GHB and 13.5kg of precursors.

Also found were an amount of substances believed to be cocaine, steroids and methylamphetamine, ammunition, and equipment used to manufacture drugs.

Drugs with an estimated street value of $5.2 million were uncovered in aa raid on a rural property in Calf Farm Road at Mt Hunter, west of Camden, on October 24. (NSW Police)

Among the 450 items seized were more than 21kg of MDMA powder and pills, 28 litres of GHB and 13.5kg of precursors. (NSW Police)

It took officers four days to seize the items.

A 39-year-old man was charged with a raft of drugs offences and has been remanded in custody after he was refused bail.

He will appear at Campbelltown Court on December 19.

In December 2016, detectives from the State Crime Command’s Criminal Groups Squad established Strike Force Lovelle to investigate the manufacture of prohibited drugs across NSW.

As a result of their inquiries, detectives executed a crime scene warrant at a home in Carrolls Road, at Menangle in Sydney's south-west, over an alleged clandestine laboratory in May 2018.

Police seized 200 items, including 1.4kg of prohibited drugs and equipment used to manufacture drugs.

Detectives are investigating links between the two properties, which are located just 16km apart.

State Crime Commander Acting Assistant Commissioner Stuart Smith said there had been a 47 percent increase in clandestine laboratories being located and dismantled over the last financial year.

“After dismantling one of the biggest clandestine laboratories in recent times, those involved in the manufacture and supply of prohibited drugs should know that the net is closing in on them,” Acting Assistant Commissioner Smith said.

“There is no quality control in illicit substances and the community should be aware that there is no way of knowing what you are ingesting and how it will affect you.

“We will continue to dismantle and disrupt these criminal drug enterprises and stop this poison from hitting our streets.”

Investigations under Strike Force Lovelle continue.