Australian police said they had arrested four people and seized 239 kilos of methamphetamine, or ice, in the country’s biggest bust of its kind.

The drug would have been worth up to $54 million on the streets and was found in a series of raids across Sydney and Perth, in which cash and a loaded semi-automatic pistol were also uncovered.

The previous biggest seizure of methamphetamine was 219 kilograms in Melbourne in 2008.

Of the four arrested, two were Australian, aged 38 and 21. Another was a Dutch national, 43, and the last a 41-year-old from Belgium, both described by police as “highly placed members of a sophisticated global syndicate”.

Federal Police Assistant Commissioner Kevin Zuccato said the two Europeans were running the operation out of Sydney’s eastern suburbs, where they provided safe houses to store the ice. Three of the men have been charged with trafficking commercial quantities of controlled drugs and the other with possession.

“This investigation strikes a significant blow to organised criminal groups operating in Australia,” said Mr Zuccato.

He added that the sophistication of transnational crime syndicates and the strength of the domestic currency was making Australia an increasingly popular target for drug trafficking operations.