The European Commission issued an ultimatum yesterday against European airline ticket selling websites, threatening to take legal action if they fail to correct misleading advertising and unfair practices.

"It is unacceptable that one in three consumers going to book a plane ticket online is being ripped off or mislead and confused," said European Union (EU) Consumer Commissioner Meglena Kuneva.

An EU-wide enforcement investigation, which started in September last year, showed one in three websites had required follow-up enforcement action for breach of EU consumer law.

The problems, such as misleading pricing, irregularities related to contract terms and non-availability of advertised offers, exist across the airline industry as a whole.

"My message to industry is clear, act now or we will act," Kuneva said.

"We will need to see credible evidence of improvement to clean up these sales and marketing practices within the airline sector by May 1 next year or we will be left with no choice but to intervene," she added.

The Commission said it will monitor developments in the airline sector over the coming year and assess the need for further action at that time.