A group of European booking sites has penned a statement calling Lufthansa Group’s planned surcharge on bookings outside its direct channels “manifestly illegal.”

Etraveli, e-Travel, the Lastminute.com Group, Travelgenio, Travelplanet24, Travix, Unister Travel, and eDreams Odigeo all signed on to pressure Lufthansa to drop its upcoming surcharge on bookings made using global distribution systems. All of these sites use such systems to process travelers airline bookings.

“The surcharge which will be applied by the Lufthansa Group airlines will have a significant negative impact on consumers and the industry as a whole as it will limit choice, increase prices, reduce fare transparency, and restrict agents in their ability to serve their customers,” according to the statement made on behalf of these online travel agencies by European law firm Simmons & Simmons.

Lufthansa is trying to incentivize consumers to book on the airline’s own websites, and the statement claims that discriminating against select booking channels violates competition law in the EU and amounts to a “price fixing conspiracy” by airlines against online travel agencies.

“A formal complaint has already been filed with the European Commission by the European Travel Agents and Tour Operators Association and the OTAs understand that further complaints will be filed in Europe and also with local competition regulators by various consumer and travel associations,” says the statement.

The 16 euro surcharge would go into effect on September 1 and Lufthansa Group said the fee will have a neutral effect on its overall business during a financial call with analysts earlier this month.

It’s currently unclear whether the travel sites will choose to pass the surcharge onto consumers as a fee or cease booking Lufthansa Group flights altogether.

“This is a decision that they may have to make when the surcharge becomes effective, but for obvious reasons each of the OTAs will have to make its own decision,” said Koen Platteau, partner at Simmons & Simmons.

U.S. booking sites, likewise, are opposed to the surcharge.

“These actions run counter to the travel marketplace goals of efficiency, transparency, competition and consumer choice that have made travel such an important economic engine in the United States and other countries around the world,” reads a statement from Travel Tech, which represents the interests of U.S. online travel agencies and global distribution systems. “It is particularly important that consumers not be financially penalized for using travel tools that allow them to comparison shop for airline travel or manage business travel.  Even if the number of airlines from which to choose has diminished over time through consolidation, consumers should still be able to shop in an open, transparent marketplace.”

Photo Credit: A Lufthansa Airbus A340-300 lands in Ottawa. Doug / Flickr.com