International passengers are being warned to expect delays on Thursday as Customs officers strike at airports around the country.
Customs officers at Sydney, Perth and Melbourne airports walked off the job at midnight for 24 hours over a wage dispute.
Customs says air and sea passengers should allow extra time to clear border checks.
The ABC reports there are concerns the strike could affect delegates arriving in Perth for a meeting of Commonwealth heads of government.
People arriving or departing on cruise ships at Sydney's Overseas Passenger Terminal in Circular Quay may also experience delays.
The Community and Public Sector Union says industrial action will not end until the federal government confirms a wage deal which is above the rate of inflation.
The ABC reports the union has already rejected a 3% pay rise on offer.