Delays are building at major airports nationwide because of a system outage at international check-in points.

The Australian Border Force confirmed the service provider who manages the advanced passenger processing systems was experiencing an IT outage.

The issues are affecting all international check-in points across the major cities.

“We are working with the service provider to assist with resolving the matter urgently,” a spokeswoman said on Thursday.

“The ABF will revert to manual processing of passengers where applicable.”

Earlier Melbourne Airport spokesperson Andrew Lund said the ABF outage had caused widespread issues.

“We do have quite long lines at international check-in at the moment,” he told Melbourne’s 3AW.

“The problem is there’s a systems outage with the ABF, we understand it’s a nationwide outage and it’s affecting all airlines.

“Check-in is still happening, but it’s just happening a lot slower than it typically would.”

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Mr Lund said the issue was also causing problems at other airports. It is understood that there are also outages in Sydney.

Delays were also reported in Brisbane, although airport management there tweeted that it had been told it was not experiencing the same issues as other Australian airports.

“However, we are monitoring the situation. Please contact your airline for up-to-date flight information,” it said.

It is unclear when the outage will be fixed.

-with AAP