Australian budget airline Jetstar Asia Airways Pte is investing US$500 million (AU$467.81 million) to add seven new planes to its fleet and expand its route capacity from Singapore's Changi Airport, news reports said.

Jetstar, a unit of Australia's Qantas Airways Ltd, plans to increase its 14-plane fleet to 21 by the end of this year as it adds flights from Singapore to Beijing and Ningbo in China and to Hanoi in Vietnam, the Straits Times newspaper reported on Saturday.

Jetstar chief executive Bruce Buchanan said he expected the company to expand its fleet four or five times by the end of this decade in the Asia-Pacific market to 450 aircraft.

"This is a market of 450 aircraft and we are now at just 20 percent of that," Buchanan was quoted as saying.

Buchanan said his airline saw a good potential in other markets, including Indonesia and Japan.

Meanwhile, Singapore Airlines Ltd said it planned to increase the frequency of its flights to 12 destinations from the end of October to March. Singapore's flag carrier said its weekly flights to Guangzhou, China, would double to 14 and those to Bangkok would increase to 35 from 28.

Singapore Airlines would also increase its weekly flights to Mumbai to 17 from 14. It would also resume twice daily service to Tokyo's Haneda airport as travel demand picks up after the March earthquake and tsunami and subsequent radiation scare.

Singapore Airlines said its subsidiary SilkAir would also increase flights to Chengdu and Chongqing in China and Bangalore in India.