An investigation began in December when Australian Border Force detected about 100kg of the drug concealed in a consignment of benchtops from Iran.

The consignment was then taken to a clandestine laboratory in Lakemba in early January, where police say the drugs were extracted in "extremely unhygienic and toxic conditions".

Another three shipments were subsequently uncovered by police, including 90kg stashed in two loads of chandeliers.

All up, about 250kg of meth, worth about $187 million, was discovered in four consignments.

Australian Federal Police searched the Lakemba warehouse as well as houses in Blacktown, Merrylands and Doonside on January 8 and 9.

A 30-year-old man and 26-year-old woman were arrested. Both have been charged with importing a commercial quantity of border controlled drugs and face a maximum penalty of life in prison.

"Australians are among the highest per capita users of methamphetamines and that means we have to be ever vigilant for syndicates that seek to exploit this devastating drug to line their own pockets," AFP Acting Commander of Investigations Geoff Turner said in a statement on Monday.

Police believe the pair were part of a broader criminal syndicate and expect further arrests will be made.

The arrested pair were denied bail, with the man due back in NSW court on Monday and the woman on Wednesday.

"No concealment is too tough for our officers, they have seen it all, and have advanced technology at their disposal to identify these illicit substances no matter how criminals try to hide them," ABF Acting Commander of Port Operations Ranj Maharaj said in a statement.

Australian Associated Press