MAJOR American airports are slowly clearing a backlog of travellers after their passport systems suffered a national outage.

International airport systems failed across the country for about two hours on one of the busiest evenings to travel in the states.

U.S. Customs and Border Protection have just announced all airports are back on line after the outage, which affected multiple major airports including JFK Airport in New York, LAX and Miami International Airport.

Another look at the backup at #Miami’s airport. Custom and Border Patrol system is down nationwide. People waiting in line for hours just trying to get home. @WPTV pic.twitter.com/W7cH1x9G0H — Chris Stewart (@CStewartWPTV) January 2, 2018

“During the disruption, CBP had access to national security-related databases and all travelers were screened according to security standards,” CBP tweeted.

“No indication the disruption was malicious in nature.”

Reporters and travellers at airports posted on social media about the mayhem which is still causing massive delays.

The official Twitter page for JFK tweeted: ‘Due to U.S. Customs and Border Protection computer issues, passengers at JFK Airport may experience delays in the international arrivals area.’

Footage has been posted of passengers clogged up in queues as they waited for word on when the computers would be back up and running.

One person tweeted that Miami Airport is “total chaos” while another said the lengthy lines at JFK “are horrible”.