Tiger, whose parent company is Singaporean, said the Civil Aviation Safety Authority (CASA) had served it a "show cause" notice last month threatening to vary, suspend or cancel its licence.

Reportedly related to training and monitoring of pilots and maintenance, it is the first such notice to be issued to a major Australian airline since 2001, when CASA threatened to ground the now-defunct Ansett Airways over jet safety.

A Tiger spokeswoman stressed that there were no serious safety concerns but declined to comment on the details.

"CASA asked Tiger to clarify certain matters, which Tiger has responded to promptly and in full," the spokeswoman said.

"Basically what they've done is they've asked for a few corrective measures -- those were implemented,' she added.

"If CASA had any concerns they would certainly shut us down. That hasn't occurred. We continue to operate with CASA's approval."

Regulators were now believed to be considering Tiger's response to the notice.

CASA told AFP it was not "saying anything really except that we don't comment on show cause notices."

It came as Tiger cancelled several services in Australia, stranding hundreds of passengers ahead of a five-day break to mark Easter and a war veteran's holiday -- traditionally one of the busiest times for airlines.

Tiger said the cancellations were not due to the show cause notice but related to "operational issues".

Passengers would receive a full refund, credit to fly at another time or could be transferred to another Tiger flight of their choice, the spokeswoman said.

Tiger Airways Australia is a subsidiary of Singapore-based Tiger Airways Holdings, which is part-owned by Singapore Airlines. It has been flying in Australia since 2007 and last month celebrated its seven-millionth passenger with a $1 fare sale across 19 domestic routes.

It describes itself as Australia's "only true low-fare airline" and has reportedly driven down domestic ticket prices by 30 percent since entering the market.