Pseudoephedrine is often found in cold and flu tablets and is a key ingredient in the production of methamphetamine.

The raid is expected to stop more than $200 million worth of methamphetamine from reaching the streets.

Police believe the drugs arrived at Port Melbourne hidden amongst 900 boxes of washing powder in a container from Vietnam on December 9, 2016.

The consignment was found at a factory in Tottenham after authorities conducted eight raids in Melbourne's west across Burnside, St. Albans, Sunshine and East Keilor.

The raid came as a part of Operation Haughton, a joint investigation between Victoria Police, the Australian Federal Police (AFP), the Australian Border Force (ABF), and the Australian Criminal Intelligence Commission (ACIC).

Intelligence agencies claim that the raid has "dismantled [the syndicate] from the top down" in Australia.

"It's safe to say that a syndicate such as this doesn't operate in isolation just here in Australia. Clearly we've got connections into Vietnam, as that is where the product has emanated from, and we'll be conducting other investigations as the investigation unfolds," said AFP acting state manager Matt Warren.

The syndicate was also allegedly responsible for a clandestine laboratory in Werribee, which police shut down in October.

Acting Commander Paul Naylor said that Victoria Police "won't be taking their foot off the pedal" in the battle against drug distribution.

"It sends a pretty clear message that you will be found and that Victorians are prepared to come forward and give information at the right time," he said.

The suspects, aged between 27 and 48, were charged with drug importation offences and are in custody awaiting trial.