Australian authorities have seized 500kg of drugs shipped from China and arrested four people including a26-year-old Sydney man in connection with the case.

The drug haul included approximately 159 kilogrammes of methamphetamine and 340 kilogrammes of the drug precursor ephedrine.

The arrested men will be presented in court on Friday, the Australian Federal Police (AFP) said.

Australian Border Force (ABF) zeroed in on the three sea freight containers from China early this month.

AFP's investigations, codenamed Operation Serpi, resulted in the rug haul and arrest of the people, Channel News Asia reported.