BERLIN (Reuters) - German federal prosecutors have charged a German citizen with espionage, saying he passed floor plans of the Bundestag parliament building to Russian intelligence. The man, identified only as Jens F., obtained PDF files with the floor plans during the course of his work for a company that was hired to maintain electrical equipment in the Bundestag’s buildings, the prosecutor’s office said in a statement. The charges could further strain ties between Russia and Germany, which protested at the arrest of Kremlin critic Alexei Navalny shortly after he returned to Russia from months of convalescence in Germany following his poisoning, allegedly by Russian state security services, last year. According to prosecutors, the suspect decided in 2017 to pass the floor plans to Russian intelligence. He sent a data storage device to an employee at the Russian embassy who mainly worked for Russian intelligence agency GRU, they said. This is not the first occasion in which Russian security services have allegedly spied on Germany’s legislature. In 2016, German authorities said the Bundestag’s computer systems had been the victim of a Russian hacking attack the year before. Reports of further spying could strengthen the hand of opponents of the Nord Stream 2 gas pipeline that is due to link Russia and Germany under the Baltic Sea. Critics, including the United States, say the project heightens Germany’s dependence on energy from an unreliable and potentially hostile partner.