Border Force officials with their "hands in pockets" or taking strike action were putting Australia's national security at risk, Immigration Minister Peter Dutton said on Thursday.
The minister's comments follow claims by the federal workplace authority that Border Force public servants had better jobs than most Australians who "must be wondering what all the fuss is about".
As the hearing on the right-to-strike between the Immigration Department and the Community and Public Sector Union goes into another day on Friday at the Fair Work Commission in Melbourne, Mr Dutton backed his department in its claims that security was being put at risk by the industrial action.
The minister told a Sydney radio station that Australia was "not immune" from the type of terrorist attacks seen recently in Europe and national security could be at risk if further strikes occurred.
"If we have got people standing with hands in pockets or on strike, not doing the work that is needed to be done, it does create a national security issue for us," he said.
"I think there is a very strong argument for there not to be strike action."
Meanwhile the Agriculture Department says it warned its public servants they would be punished for striking at airports and the Immigration Department is going back to the industrial tribunal to try to prevent its own workers taking stop-work action.
Striking quarantine officials at sea ports and airports around the country were stood down and docked pay by their employer, the Agriculture Department, which accuses them of endangering the nation's biosecurity.
The department defended the move, telling Fairfax that fair warning was given to public servants planning to strike.
"The department gave notice on March 31 that any staff participating in partial work bans would not be entitled to payment on the day of this action," an unnamed spokesperson said.
"High employee participation in rolling partial work bans and the extended period of coverage of this action has the potential to adversely impact biosecurity outcomes, given the limited capacity of the department to inspect a significantly increased number of passengers referred for intervention."
In his latest foray into the dispute at the Immigration Department, Public Service Commissioner John Lloyd claimed that public servants working there, including Border Force, had better working conditions than the majority of the Australian workforce employed by the private sector, and that their union, the CPSU, was engaged in "old-fashioned union militancy".
"It ... is remarkable that the CPSU is running such an aggressive industrial campaign in the Department of Immigration and Border Protection," the commissioner said.
"By any measure, the conditions in the DIBP agreement are good and well in excess of what many in the private sector enjoy.
"Most people would be wondering what all the fuss was about."
The Immigration Department is back in the Fair Work Commission looking to stop its Border Force officials from taking strike action, arguing that the stop-work protests are endangering national security.
But the claims by the department are either false or overblown, according to the CSPU, which is fighting the case.