Police are investigating whether four people arrested over a drug bust in the state's central west have links to the Italian mafia.

An operation saw four people arrested near Bathurst yesterday after raids on a property found large cannabis crops, with officers seizing $1.7 million worth of the plant.

Police described the cultivation of the illicit drug at Mt Rankin as crops that looked like "football fields" from the air.

Two teenagers, a 41-year-old and a 72-year-old man were arrested; three of them were Italian nationals on student visas.

Detective Superintendent Peter McErlain from the State Crime Command said links with foreign crime syndicates were being investigated.

He said the three Italian nationals appeared to be from the same family.

"We are looking into that at the moment, but because they are Italian nationals there are some details we need to check with Interpol so those inquiries are continuing," Detective Superintendent McErlain said.

Multiple raids, more than 20 arrests

One of two drug labs found by police in Neville near Blayney and Moorebank in Sydney. ( Supplied: NSW Police )

The arrests coincided with multiple other drug raids across regional New South Wales and south-west Sydney yesterday.

Between separate joint investigations, and the State Crime Command operation, more than 20 men were arrested yesterday following searches in Parkes, Forbes, Sydney, and the Illawarra district.

One 39-year-old was charged with 185 offences, including the supply of a commercial quantity of methylamphetamine.

Two large-scale drug laboratories were found and dismantled in Neville near Blayney, and in Moorebank in Sydney's south-west.

Police seized $4.5 million worth of MDMA and found more than $100,000 in cash between the two labs.

Superintendent Chris Taylor from the Central West Police District says the operation his officers helped carry out was one of the biggest they had conducted.

"In the central west, it is one of the largest we have had," Superintendent Taylor said.

"It has been 12 months in the making. We began this in March last year with information that was provided by members of the community."

Several people were expected to face court today.

Police said further arrests were expected to be made.