Travel booking site Priceline has edged up the list of the US's most popular travel websites, overtaking TripAdvisor which has fallen from third to fifth place in two weeks.

Priceline recently launched a new version of its iPhone app, allowing users to book rooms on the go using their mobile phone and find hotels by pointing their iPhone in a certain direction using the "hotel radar" service. The free app is currently the 13th most popular Travel app in the US app store.

TripAdvisor, meanwhile, has been facing criticism in the UK and US about the accuracy of its reviews. In the wake of its 2010 list of "dirtiest hotels," several establishments have lashed back against reviews they claim are inaccurate and malicious. A recent investigation by travel website Travolution found that hotels are regularly approached by agencies offering to post fake reviews in return for a monthly fee. TripAdvisor has fallen two places amongst US websites in the past two weeks.

In Canada however, TripAdvisor remains the second most-popular non-mapping travel website, losing first place to Expedia. Canadian flag-carrier Air Canada is the third most popular, followed by low-cost airline Westjet.

Amongst Australian internet users, the fastest-moving (gaining) search term this week was "formule 1 sydney airport." Last month, the Formule 1 budget hotel at Sydney's International Airport unveiled a $7 million extension, and reported a 13.7 percent jump in room reservations for January. It now has over 200 rooms and says that customer bookings have been particularly high from UK, Ireland, Eastern Europe and New Zealand.

The most popular travel websites in the US
Data from Experian Hitwise for week ending February 6, mapping websites excluded

1. Expedia 3.39%
2. Southwest Airlines 2.19%
3. Travelocity 2.12%
4. 1.85%
5. TripAdvisor 1.66%
6. Orbitz 1.63%
7. Delta Air Lines 1.28%
8. Yahoo! Travel 1.22%
9. Hotwire 1.21%
10. 0.98%