Five men have been charged with drug importation offences after police seized up to 300 kilograms of pure pseudoephedrine disguised as washing powder in a Melbourne factory.

The drugs were seized following a investigation involving the Australian Federal Police (AFP), Victoria Police, Border Force and the Australian Criminal Intelligence Commission (ACIC).

The five men, aged between 27 and 48, were arrested on January 7 after authorities searched eight locations in the Melbourne suburbs of Burnside, St Albans, Sunshine, East Keilor and Tottenham.

All five appeared at the Melbourne Magistrates Court over the weekend and were remanded in custody to re-appear next month.

Police will allege the pseudoephedrine, which arrived in Melbourne from Vietnam on December 9, was transported in 57 boxes hidden amongst more than 900 boxes of washing powder.

Pseudoephedrine, an ingredient in some cold and flu medications, is used in the manufacture of methamphetamine, also known as ice.

Seized drugs worth ‘in excess of $200 million’

Border Force officers, using intelligence provided by the ACIC, examined powder found in a consignment at a factory at Tottenham, which tested positive for pseudoephedrine.

The AFP said the pseudoephedrine was mixed with a white powder, which together weighed about one tonne.

It estimated the mix contained 300kg of pure pseudoephedrine, which has a wholesale value of $42 million and a street price in excess of $200 million.

Police will also allege the syndicate was responsible for a lab found at Werribee, about 30 kilometres south-west of Melbourne, which produced more than 500 kilograms of ice.