German Chancellor Olaf Scholz promised swift clarification on Saturday following the Russian publication of a recording of German air force officers discussing support for Ukraine.
Speaking on the fringes of a visit to the Vatican, he described it as a "very serious matter."
The conversation between German defence officials was published on Friday by the head of the Russian state broadcaster RT, Margarita Simonyan.
In it, senior air force officers discuss the theoretical possibilities of a deployment of German Taurus cruise missiles in Ukraine.
Scholz has repeatedly ruled out the supply of Taurus missiles to Ukraine, despite repeated requests by Kiev, arguing that he fears Germany could be drawn more deeply into the war launched by the Kremlin in February 2022.
The clip also contains a diplomatically sensitive reference to the British having "a few people on the ground" in Ukraine, in connection with the deployment of their Storm Shadow cruise missiles to the country.
The reference follows anger in Britain over what London saw as previous indiscretion on Scholz's part.
Scholz had said, in the context of the Taurus debate, that "what the British and French are doing in terms of target control and accompanying target control cannot be done in Germany," without elaborating further.
Some saw this as an indication that French and British forces are supporting the control of cruise missiles supplied to Ukraine. London immediately denied this was the case.
Pressed by a dpa correspondent on Saturday about possible diplomatic fall-out from the intercepted Bundeswehr exchange, Scholz said: "That is why this is now being clarified very carefully, very intensively and very quickly. That is also necessary."
Air Force inspector Ingo Gerhartz was among those present at the meeting, which is said to have been in preparation for a briefing to Defence Minister Boris Pistorius.
The exchange heard in the recording addresses whether Taurus cruise missiles would theoretically be technically capable of destroying the bridge built by Russia to the Ukrainian peninsula of Crimea, annexed by Moscow in violation of international law.
The discussion also addresses whether Ukraine could carry out the strike without the involvement of the German armed forces. It is made clear in the recording that German lawmakers are not willing to provide Kiev with cruise missiles.
Sources told dpa earlier on Saturday that the recording is genuine and that the discussion was hosted on Webex, a US-made online conferencing platform.
The German Ministry of Defence was investigating whether the communication had been intercepted. "The Federal Office for the Military Counterintelligence Service has initiated all necessary measures," a ministry spokeswoman said on Friday evening.
German security lawmakers responded with calls for improvements. "We urgently need to increase our security and counterintelligence, because we are obviously vulnerable in this area," Marie-Agnes Strack-Zimmermann, Chairwoman of the Bundestag Defence Committee, told the Redaktionsnetzwerk Deutschland (RND) news agency.
"The question arises as to whether this is a one-off incident or a structural security problem," said Konstantin von Notz, chairman of the Parliamentary Control Committee.
The publication unleashed widespread speculation about its timing, with Strack-Zimmermann speculating Russia aims to deter Scholz from giving Kiev Taurus missiles.
She told RND that espionage is "part of Russia's toolbox of hybrid warfare," adding it was not surprising that conversations were intercepted. "It was only a matter of time before it became public," she said.
Others speculated that the Bundeswehr leak could be a Russian attempt to divert the public debate away from recent revelations or the funeral of dissident Alexei Navalny.
