The German air force is facing such a severe funding shortage that many of its aircraft are unable to fly, mechanics are forced to cannibalise parts from existing planes and only eight of the country's 109 Eurofighters are fully operational, according to a report in Spiegel magazine.
German defence sources have rubbished the article, saying it is inaccurate and does not match up to official air force logs.
But the claim that Germany's air force is not as strong as previously thought will cause concern among its Nato allies at a time of growing worldwide instability.
Germany has the fourth largest air force in Europe, yet the Spiegel report suggests it is far weaker in reality than it is on paper.
Many aircraft are badly in need of repair, and spare parts are in such short supply that mechanics have resorted to taking them from existing planes, said the magazine.
The report claims the German government is now facing embarrassment because ministers promised to send six Eurofighters to the Baltic states next week despite the alleged shortfalls.
It says as few as seven of Germany's 67 CH-53 transport helicopters are fully operational, including those currently deployed in Afghanistan, and only five of its 33 NH-80 helicopters.
Of the 56 C-160 aircraft which carry relief supplies to northern Iraq, only 21 are operational, it claims.
The air force has refused to comment publicly on the report, saying it concerns classified information.
But defence sources have sought to rubbish Spiegel, saying the publication has misinterpreted an internal report. Officials said the magazine's reporters had listed some planes as unable to fly, when in fact they were only in need of routine maintenance.
The row comes against a backdrop of concern over Germany's defence budget.
Despite being Europe's biggest economy, Germany lags far behind its neighbours when it comes to defence spending.
Under a Nato agreement, members are supposed to spend at least two per cent of their GDP on defence, but Germany spends only 1.3 per cent and is planning further cuts.
Since the end of the Second World War, the country's leaders have been reluctant to get involved in military operations abroad because of historic guilt over the crimes of the Nazis.
But recently there have been growing calls for the country's military to take on a bigger international role – not least from the Defence Minister, Ursula von der Leyen.
"Indifference is not an option for a country like Germany," she said in January. She has also said Germany is "almost doomed to take on more responsibility".
But it is thought even Ms von der Leyen – who is one of the best known politicians in the country and widely seen as Angela Merkel's anointed successor – cannot take on the chancellor over defence spending. Mrs Merkel is said to be determined to present a balanced budget in 2015.
Ms von der Leyen's biggest policy so far has been the introduction of creches and flexible working hours to stave off a recruitment crisis in Germany's armed forces since conscription ended in 2011.
But the recruitment drive doesn't appear to be working yet – the German navy is short of 1400 personnel, according to Spiegel.
