Investigators have uncovered a plot to bomb a passenger plane in Germany this year using explosives which were to have been hidden in luggage, the federal prosecutor's office said on Monday.
"During the summer, several suspects made contact with an individual who had access to the security-restricted zone of an airport," a statement said.
The individual agreed to help smuggle explosives concealed in a case or a bag onto a plane in return for payment, it added.
But the plot broke down when the as yet unidentified suspects failed to reach agreement with the airport employee on the amount he would be paid to plant the luggage.
The prosecutor's office gave no details of which airport was involved.
Six suspects were arrested in Germany on Friday in connection with the plot, but five were released the following day. A sixth person was kept in custody in connection with a different offence.
All six suspects are being investigated for allegedly belonging to a terrorist organisation.
Investigators searched nine apartments in the southern region of Rhineland-Palatinate and Hesse in central Germany looking for evidence, a spokesman said.
A spokesman for the interior ministry said he had nothing to add to the information given by the prosecutor's office.
Germany was shaken this summer after it was discovered that home-made bombs hidden in suitcases failed to explode on two passenger trains. Faulty detonators prevented the explosives from detonating.
Two Lebanese men have been charged with planting the suitcases on trains heading for the western cities of Hamm, near Dortmund, and Koblenz on July 31.