BERLIN, July 26 (Xinhua) -- Undercover police officers have been put on flights of German airlines ever since the Sept. 11, 2001 terror attacks. Now, the German Federal Court of Justice ruled on Thursday that airlines are not to be reimbursed for the cost incurred by this security measure, after Lufthansa had sued.

The so-called sky marshals are specially trained police officers who fly in plain clothes and are supposed to thwart sky-high terrorist attacks.

While the Federal Police of Germany is tight-lipped when it comes to details about their special force, unconfirmed numbers suggest there were at least 200 undercover officers when the program first started.

Airlines were required to provide high-value seats to sky marshals free of charge. However, Germany's largest airline Lufthansa did not accept having to cover taxes and fees in addition for high-value seats for the special passengers. The airline demanded back more than 2.3 million euros from the German federation.

In their lawsuit, Lufthansa claimed the additional cost put them at a disadvantage with other airlines only flying domestically.

The highest German court upheld the decision made earlier by a regional court. According to the Federal Court, because international flights are more at risk to be the target of terror attacks, the extra cost for these security measures are justified.

Furthermore, the additional annual costs of employing sky marshals were "of minor economic importance" in relation to Lufthansa's 30 billion euros turnover, the court argued.

As the special police forces increased safety on their flights, the court proposed Lufthansa could add the additional cost to their ticket prices. A spokesperson for the company rejected the notion categorically, emphasizing the court's decision "naturally has no effect on the ticket prices of our passengers". Enditem