Members of the European Council and European Parliament have failed to agree on a definition of "parent carrier."
This latest stalemate comes after French and German representatives on the Council tried to dilute a strong definition proposed by the Parliament's transport committee.
More meetings between Council members, MEPs and representatives of the French government which currently hold the EC presidency are due to be held in the next week.
The matter will go back to the full session of the European Parliament in September and may also go before the Council's Committee for Permanent Representatives next week.
This impasse is the latest twist in the efforts of the European Commission to de-regulate CRSs in Europe.
In its own report, the EC recommended that while CRSs could be largely de-regulated, there must be safeguards because to prevent abuse by airlines which had effective control of a CRS.
Air France, Lufthansa and Iberia have together a stake of 46.4% in Amadeus, the biggest CRS in Europe.
But the EC confused matters when it said it did not regard any of the three as a "parent carrier."
When the issue went to the Parliament's transport committee, Timothy Kirkhope, a UK MEP, proposed a much stronger definition that any airline with a direct interest in a CRS should be regarded as a parent carrier.
This definition was approved by the committee but has now been rejected by the Council.
A spokesman for Mr Kirkhope said the MEP, members of the Council and officials from the EC would be meeting again in the next week to discuss the matter but no decisions were expected.