Russia's antitrust authority signaled Tuesday that it might block a bid by German industrial giant Siemens to take a controlling stake in a strategic engineering company, citing national security concerns, Interfax reported. "Our position on this deal is well known. Aside from anti-monopoly issues, there are questions of the country's security and defense capability," the news agency quoted federal anti-monopoly agency chief Igor Artyomov as saying. "Naturally, Siemens' dominance in this sector would increase somewhat with its arrival on the Russian market," he said. Silovye Mashiny (Power Machines) mostly makes energy equipment, but some of its plants also produce parts for the Russian defense sector, including the nuclear fleet. Siemens and the Russian holding Interros, the current owner of Power Machines, announced last July an agreement to create a joint venture that would control about 71 percent of the Russian turbine manufacturer. The deal was announced at a meeting between Russian President Vladimir Putin and German Chancellor Gerhard Schröder. But the Russian authorities have since appeared to reconsider the German takeover, because of reluctance to allow a company deemed strategic to pass into foreign hands.