New advertising rules requiring airlines and travel agents to disclose charges in full kicked in on November 1.

Nonetheless, advertisements promoting zero-dollar fares are still widespread online. Such ads normally do not include airport taxes, administrative fees, insurance and fuel surcharges, which could easily come up to at least S$200.

Not surprisingly, consumers welcome the latest move by the Advertising Standards Authority of Singapore (ASAS) which ensures that airlines and travel agencies state the price of air fares in full, inclusive of taxes and surcharges.

In response, one customer said: "You don't have to go down to the travel agency and be told that you need to pay a lot more. It's a waste of your time."

"For young people, they think S$99 means it's the fixed price. So they forget there are a lot of hidden costs into it," another added.

While budget airlines such as Jetstar Asia and Tiger Airways have said they will follow the guidelines, both have been tight-lipped about their new marketing strategies going forward.

An ad featuring zero-dollar fares for selected destinations is still up on Jetstar's website on November 2. The budget airline said preparations for this promotion were done before the new ruling was implemented.

Tiger Airways, on the other hand, may be absorbing taxes. Its website clearly states that cheap fares are subject to availability, so customers may still end up paying higher fares, if the discounted seats are sold out.

The Consumers Association of Singapore (CASE) said the new advertising guidelines will help travellers in their buying decisions. But this new ruling will not help a consumer who has bought from a non-Singapore website with no office here.

If an airline or travel agent fails to comply with the new ruling, the ASAS can ask media owners not to accept ads from these companies or name the offenders publicly.