Sydney is about to become the centre of a fare war between budget airlines after Malaysia's low-cost long-haul carrier AirAsia X confirmed it will begin flying between Kuala Lumpur and the harbour city from April.

Six weeks after Singapore Airline's new budget offshoot, Scoot, announced that it would begin daily services to Sydney from the middle of this year, AirAsia X today confirmed the worst-kept secret in aviation by declaring that it would fly daily between Sydney's Kingsford-Smith and KL from April 2.

Air Asia is expanding its budget offerings to Australia.

To lure passengers on to its flights, the long-haul affiliate of Asia's largest budget airline AirAsia is offering one-way launch fares as low as $99 and premium seats for $499.

The arrival of both AirAsia X and Scoot at Australia's biggest airport will intensify pressure on Qantas's budget offshoot, Jetstar. AirAsia X already flies to the Gold Coast, Melbourne and Perth from Kuala Lumpur.