Turkish defence analyst and founder of the opposition Democracy and Progress Party (DEVA), Metin Gurcan. Photo courtesy of Metin Gurcan Twitter account.
Gurcan, a former member of the Turkish military, was one of the co-founders of DEVA party led by Ali Babacan, a former deputy prime minister within President Recep Tayyip Erdogan's ruling AKP party.
Turkish police detained him on Friday.
"I am being detained on charges of political espionage. The police are at home... They are searching. I am shocked and I seek your help," Gurcan tweeted last week.
Gurcan was then jailed on Monday, according to the private NTV broadcaster.
"As far as we know, Metin (Gurcan) has no means to access to any classified state document," Babacan told Haberturk television. "Because he is not working for the state."