Ryanair has made a formal complaint to EU competition commissioner Mr Mario Monti, accusing Lufthansa of engaging in "dirty tricks".
Ryanair is accusing the German airline of engaging in measures designed to prevent German consumers and visitors availing of lower fares.
Ryanair confirmed today it would be appealing against the decision of the Cologne Court to grant an injunction to Lufthansa to prevent Ryanair using comparative advertising in the German market.
Ryanair chief executive Mr Michael O'Leary said: "It's typical of a monopoly airline like Lufthansa, who cannot match Ryanair's fares and who don't want to offer the German consumers lower air fares, to run into court at the first possible opportunity".
Mr O’Leary accused Lufthansa of trying to block competition in Germany instead of lowering its air fares. He said Ryanair will continue its advertising campaign.