To celebrate its much-awaited entry into the market, Indonesia AirAsia - an associate of the Malaysian budget carrier - will launch four new routes on the same day.

From March 24, it will start twice-daily services between Singapore and Jakarta; and once a day to Bali, Bandung and Yogyakarta. Singapore's Tiger Airways will launch daily services to Jakarta from March 29. The airline has also been given rights to fly to Bali.

On Sunday, AirAsia ended a week-long promotion; giving away more than 50,000 free seats. Taxes and other charges cost more than $70 for a return trip. Tiger's sale started on Friday. All-inclusive fares are going for $76.

The launch of Singapore-Indonesia services is significant for the two carriers which had before this, been barred from entering the market.

In 2004, Indonesia imposed a blanket ban on budget carriers - a move seen as a way to protect the country's fledgling carriers. Restrictions were recently lifted as part of a wider move towards air liberalisation in the region.

The boost in flight numbers and attractive fares are expected to further stimulate demand in what is already one of the region's busiest air markets.

According to official data, visitor arrivals from Indonesia hit 1.77 million last year.

Although it was a 10 per cent drop compared to the year before that, Indonesia remains the top contributor of arrivals to Singapore.

Despite the economic slowdown, AirAsia's regional head of commercial, Kathleeen Tan, expects demand for Singapore-Indonesia flights to stay strong. At a media event on Monday to celebrate the launch of the airline's new routes, she said: 'We are very upbeat about prospects in this market. People still want to fly and if you give them low fares, they will fly.'

The airline expects to fill seven out of 10 seats in the first few months of operations, and eventually take this to over 80 per cent, she said, adding that AirAsia has ambitious plans and is eyeing up to five daily flights between Singapore and Bali.