MEPs on the European Parliament's transport and tourism committee are split over how and whether to change the definition of 'parent carrier.'
The MEPs considered a report by Timothy Kirkhope, a UK Conservative MEP appointed as "rapporteur" to the committee on the planned revision of the CRS code of conduct for two days earlier this week.
Mr Kirkhope, a lawyer, recommended a tougher definition of parent carriers as any airline which had a stake in a CRS.
The EC report on the meeting said: "While some Members considered this position balanced, others were proposing to go further with a total unbundling with regard to the ownership of the airliners into the CRSs and others don't see a real reason for amending the existing definition."
Mr Kirkhope recommended extending the definition of 'parent carrier' to one which includes an airline or train operator which "participates in the capital, effectively controls, or has the legal right to nominate any executive or any member of the board of directors, supervisory board or other governing body."
In an additional amendment to the EC's revised code, he said that details of any capital holding by an airline or train operator in a CRS or any stake of a CRS in a carrier or rail operator "shall be publicly disclosed."
His recommendation follows the EC report which said there should be safeguards to protect against any potential abuse by parent carriers.
But the EC then said that it did not regard Air France, Iberia and Lufthansa which together have a 46% stake in leading CRS Amadeus as 'parent carriers.'
The EC report said the debate on parent carriers at the transport committee had been "animated."
But it said that Mr Kirkhope's recommendation that regulations on Marketing Information Data Tapes (MIDT) should "leave open the possibility to allow travel agents to negotiate with CRS on their identification" was accepted by the MEPs.
This clause has angered agents' associations in Europe which want to retain the anonymity of travel agents.
A statement by the UK Guild of Travel Management Companies (GTMC), backed by the Guild of European Business Travel Agents (GEBTA) and the European Travel Agents and Tour Operators Association (ECTAA) said the anonymity clause had only been included after "comprehensive lobbying last year."
Philip Carlisle, the GTMC's ceo, said: "This is a very worrying development. A decision to overturn this privacy clause could lead to an influencing of travel management companies sales strategies by airlines, distort competition for the distribution of air tickets and damage the sector by freezing competition in air transport."
MEPs will be able to table amendments to Mr Kirkhope's report up to April 22.
Any amendments will be considered and voted on on May 27-28.
The final report will go before the full Parliament in July or September.