Australians wanting to emigrate or travel to the United States are being held up by technical issues affecting the US State Department's visa systems.
The US has been unable to properly process visas, passports and travel documents since last week due to unspecified "technical problems" with its Oracle-based database.
The US Embassy in Canberra said it was unable to print most immigrant and non-immigrant visas approved after June 9 following a hardware failure that same day. New applications submitted after that date are also currently unable to be processed.
US passport applications accepted overseas after May 26 are also affected, but the State Department said it is now able to start issuing those passports again. Passport applications submitted inside the US have not been affected.
The unidentified hardware failure meant biometric clearance requests stopped flowing from embassies to the US 'consular consolidated database' (CCD), resulting in a big backlog.
"The systems in place to perform required national security checks before we issue visas are experiencing technical difficulties. As a result, we are unable to print visas," the US State Department advised.
"We cannot bypass the legal requirements necessary to screen visa applicants before we issue visas for travel.
"As a result, there is a backlog of visas waiting to be processed. We are working as quickly as possible to resolve the issue and to clear the backlog."
The US embassy in Canberra advised those who had appointments for visa interviews listed for between June 14-20 to reschedule if their visa application had been submitted after June 9.
The overall issue was not specific to any one country or visa category, the State Department advised.
It did not provide a cause for the outage.
The department said overseas passport applications accounted for less than five percent of its annual passport workload.
The CCD suffered a week-long outage last August, but the department was at pains to stress the current issues are not related to that incident.
A software upgrade was blamed for the system crash last time around.
The department was similarly keen to emphasise that it had no evidence to suggest the latest issues were related to any breach of cyber security.
Affected were visa issuance, consular reports of births abroad and the ability for US citizens to obtain passports overseas. The department was able to process urgent requests, it said.
The CCD has been described as "one of the world's largest Oracle-based data warehouses".
It stores hundreds of millions of visa files and links to other critical US systems including the FBI's integrated automated fingerprint identification system, Homeland Security's automated biometric identification system, and the State Department's facial recognition system.