Turkish authorities have detained the owner and general manager of Assan Group, a defense and construction conglomerate, as part of a military espionage investigation, the Istanbul prosecutor’s office said late on Wednesday.

Axar.az informs, citing Reuters, the prosecutor’s office said the two men — identified as company owner Emin Oner and general manager Gurcan Okumus — were being held on suspicion of military espionage and membership in the network of US-based cleric Fethullah Gulen, which Ankara accuses of orchestrating a 2016 coup attempt.

Searches were continuing at their homes and offices, while 10 companies operating under the Assan Group were placed under trustee management by the Savings Deposit Insurance Fund (TMSF), the statement added.

Okumus is a former head of TUBITAK SAGE, a state defense research institute that develops munitions and missile systems.

Assan, founded in 1989, has operations in defense, construction, logistics and energy, and in recent years expanded into producing artillery ammunition and drone components.

“The investigation is continuing in multiple directions,” the prosecutor’s office said.