The Malaysian budget airline was forced to cancel the flights after it failed to gain approval for the new route, which was due to start on December 26, from Australian and Indonesian aviation authorities.

This is despite the airline advertising and taking bookings for the direct flight as recently as this month.

Passengers received text messages on Christmas Day notifying them that flights from Boxing Day onwards had been cancelled and they would instead be flown to Bali via Kuala Lumpur, Malaysia, on a later flight.

The new route stretches a six-hour journey out to 13 hours and some travellers will arrive a day later than expected, leaving pre-booked accommodation wasted and forcing some to miss family weddings.

The airline would not reveal how many passengers had been affected but Melbourne woman Oliva Canning, who was on the first diverted flight on Boxing Day, said that most passengers on the near-full plane had been originally booked on the direct flight.

Angela Menz, also from Melbourne, was due to fly direct to Bali at 6.30pm on Saturday, only to learn she would not depart until 1.45am on Sunday.

"On Christmas Day I got a text to say the flight had been changed and that it was now going via Kuala Lumpur," Miss Menz said.

"I'd pre-booked my hotel accommodation and paid for it and airport transfers, so that's all gone to waste.

"We were originally arriving just after 10pm tonight, but now I'm not arriving until the next day at midday."

When Miss Menz, who was travelling to Bali for a one-week holiday with her boyfriend, called the airline, she was told the last-minute change was due to an "administrative issue".

She said she chose to fly with AirAsia after it had heavily advertised direct flights.

Other passengers took to the airline's Facebook page to vent anger over the disruptions.

"Thankyou for wrecking our family Christmas and my daughters wedding (sic)," Julie Chumbley wrote.

"My daughter is due to be married on the 28th dec 2014 in bali and my daughter in law is a bridesmade and my son is walking her down the isle.

"This was until you changed my daughter in laws and sons Direct flight from the 27th dec 2014 to leave on the 28th dec with a stop over in kuala lumpa in which they will miss the whole wedding!!"

Another passenger, Melissa Cook,  posted: "It's 1.45am, Xmas morning & I've just received a text advising that my direct flight tomorrow morning (26/12) has been cancelled!!!!

"Advertising was fierce for sucking Australian consumers into thinking that you would really be flying Melbourne to Bali direct from 26/12!"

Passengers do not yet know if return flights will go direct to Melbourne or via Kuala Lumpur.

An AirAsia X spokesman said the flights were diverted because of "an unforeseen delay in the approval process for necessary documentation."

The spokesman said the airline was working with relevant authorities, including Indonesia's Directorate General of Civil Aviation and Australia's Civil Aviation Safety Authority, to complete the required documents for the flights to go ahead.

"Indonesia AirAsia X will commence the direct return flight from Denpasar to Melbourne as scheduled as soon as this process has been completed," he said.

The airline would not reveal how many passengers had been affected.

In November it emerged that in the first nine months of 2014, the Malaysian carrier had lost $96 million before tax in the Australian market.

The airline announced three weeks ago that it would discontinue direct flights between Adelaide and Kuala Lumpur.

AirAsia has been contacted for comment.

Do you know more? contact patrick.hatch@fairfaxmedia.com.au