The immigration department's online service has gone down.
The ImmiAccount website on Wednesday afternoon posted the message: "Unplanned System Outage. ImmiAccount is currently unavailable. Technical teams are investigating the issue."
The service allows users to lodge a visa or citizenship application and check the progress of applications.
The department said in a statement to AAP there were "IT issues" affecting the call centre, website and emails.
"All of our systems which are critical to the security of the Australian border continue to function as normal," the department said.
"These issues are in no way linked to those experienced by the Australian Bureau of Statistics."
The ABS has temporarily taken down its census site and launched an investigation after a series of "denial of service" attacks which are believed to have come from overseas.
