From Jan 12, citizens from countries granted visa waivers, which includes Singapore, must apply online for permission to enter the US before they fly there.

Both information and applications about the Electronic System for Travel Authorisation (ESTA), are provided free by the US Department of Homeland Security.

Yet, websites, offering downloads or CD-ROMs containing information, or people who will undertake the application process on a traveller's behalf, have sprung up.

On Thursday, an official statement from the US authorities in Washington said these businesses and websites are 'not endorsed by, associated with, or affiliated in any way' with the US government.

Also, 'use of a private service to apply for travel authorisation via ESTA will not expedite the granting of approval', it said.

A check by The Straits Times found at least three websites offering this service. They charge from about US$50 (S$75.73) for an e-guidebook on the visa waiver programme, US$100 for a data CD of the guidebook, and about US$250 for a 'travel specialist' to submit the application on the traveller's behalf.

These websites carry official-looking logos with American symbols like the bald eagle or the Statue of Liberty, although they also state in the fine print that they are not affiliated with the US government.

Chief executive of the National Association of Travel Agents Singapore Robert Khoo said it would remind its members to inform their clients 'not to have to pay unnecessarily' once it had received official information from the US embassy.

A spokesman for SA Tours said it had not been informed about these unauthorised websites yet, but has been directing its customers travelling to the US to the legitimate website address.

CTC Holidays' senior vice-president for marketing and public relations Alicia Seah also said its staff would remind its group tour or free-and-easy package customers during the pre-departure briefings or e-mail messages.

However, those travellers who make their own travel arrangements may fall between the cracks, she said.

'We think these 'entrepreneurial' businesses and websites are trying to solicit customers who may be confused about these new procedures,' she said.