Immigration Minister Peter Dutton has stepped up his calls for unions to suspend rolling strikes at airports, saying the terrorism threat since the Brussels attacks has not passed.
The Community and Public Sector Union members have resumed rolling strikes at international airports around the country a week after industrial action planned for Easter was called off in the wake of the Brussels terror attacks.
Border Force officers are on strike and quarantine officers are imposing work bans, which is adding to delays.
Union national secretary Nadine Flood insists national security will not be jeopardised because officers involved had always been exempt from striking.
But Mr Dutton is unconvinced.
"The threat hasn't passed within a couple of days following the Brussels attack," Mr Dutton told ABC Radio.
"These rolling strikes aren't welcome and I hope that they come to an end sooner than later."
Ms Flood said workers were striking as a last resort, as part of a two-year negotiating battle with the federal government over pay and work conditions.
Prime Minister Malcolm Turnbull thanked airport workers for delaying the strikes at his request following the Brussels attacks, but echoed his minister in urging unions to resolve the dispute.
He assured travellers counter-terrorism services at airports were provided by the Australian Federal Police, which had planned for the strikes.
"Nonetheless, these are vital services and ... I am encouraging, asking and urging (the union) to resolve its industrial dispute by negotiation," Mr Turnbull told reporters in Sydney on Wednesday.
AFFECTED AIRPORTS
* Sydney International Airport (5am-1pm, 4pm-midnight)
* Perth Airport (3am-11am, 4pm-midnight)
* Adelaide Airport (5am-1pm, 4pm-midnight)
* Brisbane International Airport (midnight-1am)
* Cairns International Airport (4am-midday, 5pm-midnight)
* Townsville Airport (4pm-midnight)
* Darwin Airport (2am-10am, 1pm-9pm)
