Travel firm Thomson may be breaking law, Which? says
10 September 2011 Last updated at 13:11 BST
The consumers' association Which? says the UK's largest travel firm could be breaking the law because of the way it promotes some deals.
The BBC has found that Thomson, owned by TUI Travel, ran an advert suggesting only a few seats were left on a flight.
It then released more seats that were offered at a much lower price.
The Association of British Travel Agents (ABTA) said there could be more clarity in the way some offers were advertised.
Susannah Streeter reports.