European Union regulators announced on Friday two separate investigations into dodgy ticket-sale co-operation between airlines in Germany and Turkey, and Belgium and Portugal.
The European Commission said the probes, to verify whether code-share agreements were "in breach of EU rules on anti-competitive agreements," targeted arrangements reached between Deutsche Lufthansa and Turkish Airlines, and between TAP Portugal and Brussels Airlines.
"While code-share agreements can provide substantial benefits to passengers, some types of such agreements may also produce anti-competitive effects," a commission statement said.
The launch of proceedings "does not imply that the commission has conclusive proof of an infringement," the statement underlined, but "means that the commission will investigate the case as a matter of priority."
Regulators fear such arrangements "may distort competition leading to higher prices and less service quality for customers," as the operators also run parallel, direct hub-to-hub flights not covered by such agreements, The routes concerned are Munich-Istanbul and Frankfurt-Istanbul, and Brussels-Lisbon.
The commission stressed that the probes are not linked, and that there is no legal deadline for an outcome in either case.