A Qantas flight from Tonga to Sydney was delayed this afternoon after a technical issue was allegedly discovered during passenger boarding.

Emergency services contain a fuel spill from a Qantas aircraft on the tarmac. Photo/Screenshot

The incident involved QF 190, scheduled to depart Fuaʻamotu International Airport (TBU) for Sydney (SYD) at 4pm.

An apparent problem during refuelling necessitated the emergency services call as passengers were boarding, sources told Kaniva News.

As a precaution, all passengers who had already boarded were instructed to disembark and return to the departure lounge.

Video footage, seen by Kaniva News, apparently from the scene, showed emergency crews attending to a spill.

The departure was postponed pending a full assessment and resolution of the fault.

This follows last week’s emergency evacuation of a Lulutai Y12 aircraft due to a technical issue.