Last minute appeals by leading travel industry organisations against complete de-regulation of the GDSs were sent to the EC as its deadline for views closed.
ECTAA and GEBTA which represent, respectively Europe's leisure and business travel agents, called on the Commission to maintain rules to stop biased information.
It also demanded safeguards to ensure that data on agents' sales (MIDT) which is sold to airlines did not contain sensitive information.
The two bodies also want laws to stop airlines putting fares on their websites which differ to those given to the GDSs.
Jan Van Steen, president of ECTAA said: "If the European legislation is not maintained and adapted to the new market environment, then we loose the functionality of a neutral and complete display of fares provided by CRSs.
"This would bring us 30 years back, where information was completely decentralised.
"With an increasing offer of routes and fares, losing a centralised information tool would be detrimental for customers and their agents."
The EC had called for travel industry opinions as part of its latest round of consultation before it decides whether and how far to de-regulate the GDSs. The deadline for views was April 27.
The Business Travel Coalition (BTC) sent in a plea on behalf of 119 associations that safeguards must be maintained in any change of GDS regulations.
The associations included were the United Nations, the International Airline Passengers Association, the Scottish Passenger Agents' Association as well as companies like Adidas, IKEA, Thales, DuPont, Kimberly Clark, Pfizer and Bristol-Myers Squibb.
Kevin Mitchell, BTC chairman, said: "For corporate travel managers, premature de-regulation of the CRS industry in Europe represents an ominous threat to full airfare content that would needlessly plunge managed travel back into the distorted chaos of the pre-rules 1980s."
C-FARE, a body formed to fight full de-regulation of the GDSs without maintaining safeguards, also sent in a petition signed by 144 travel organisations and calling on the EC to maintain "reasonable CRS rules that will ensure fair access to reservations in Europe."
The EC was due to meet representatives of the air transport supply chain in Brussels on May 2 but no details of the meeting had emerged when BTE went to press.
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