Malaysia's no-frills AirAsia said it will not scale back expansion plans due to an outbreak of a mysterious atypical pneumonia, saying Sars was unlikely to threaten its revenue or hamper growth.

"We are doing well. We posted 400 percent growth in passenger volume for April compared to the corresponding period last year," Air Asia's chief executive Tony Fernandes told AFP.

Fernandes said while airlines were struggling globally and pursuing cost cuts, AirAsia would continue with its route and fleet expansion.

"We are undeterred. We are confident of achieving what we set off to achieve," he said.