Two officials in the German economy ministry are being investigated on suspicion of spying for Russia, according to media reports.
The weekly Die Zelt reported on Wednesday that the high-ranking officials in question are responsible for highly sensitive energy issues.
The Federal Office for the Protection of the Constitution (BfV) reportedly launched the investigation after members of the ministry voiced their suspicions.
The two civil servants are rumoured to have defended pro-Russian energy matters and criticised Chancellor Olaf Scholz for suspending the Nord Stream 2 gas pipeline.
The German Ministry for Economic Affairs and Climate Action has played a central role as the country has rapidly reduced its energy dependence on Russia following the invasion of Ukraine.
Ministry officials have not publically commented on the espionage reports.
Germany has been rocked in recent years by several espionage cases blamed on Russia. In October, a former employee of an IT security company was given a suspended prison sentence for information on the German parliament to Moscow.
A research assistant at the University of Augsburg was also convicted earlier this year for spying on the European Ariane space programme.