Lufthansa said it was co-operating fully with the European Commission
Several international airlines have been raided by European Commission officials investigating price-fixing on flights between Europe and Japan.
Germany's biggest airline Lufthansa confirmed that its offices in Frankfurt had been searched.
Sources at Alitalia quoted by Reuters said that the Italian flag-carrier had also been raided.
Surprise searches happen at an early stage in investigations and do not imply any wrongdoing by the companies.
A statement from the Commission simply confirmed that it had, "carried out unannounced inspections at the premises of a number of international airline passenger carriers".
It is not clear, how many other airlines are under suspicion.
Lufthansa explained the motive behind the raid on its offices.
"The Commission has information that passenger aviation companies including Lufthansa in Europe and in Japan may have taken part in anti-competitive price fixing and collusive behaviour in traffic between the EU and Japan," Lufthansa said in a statement.