The recent arrest by Turkey's security forces of nine people accused of spying for Iran has increased tensions between the former close allies. Bilateral relations have soured over the two countries' support of opposing sides in the Syrian conflict.
Kerem Balci, a columnist for the Turkish newspaper Zaman, says the arrests may be part of a deeper probe.
"It suggests that there should be lots of more Iranian spies working in Turkey and in fact police intelligence managed to get information from the nine people arrested that the number is about 100 Iranian spies," said Balci. "It suggests there is a kind of cold war already going on between Iran and Turkey."
What has caused alarm in Ankara is that the accused spies are suspected of gathering intelligence for the Kurdish rebel group, the PKK, which is fighting the Turkish state for greater minority rights.
It would not be the first time Tehran has used the PKK to apply pressure on Ankara, according to columnist Asli Aydintasbas of the Turkish newspaper Milliyet. She says the arrests of the alleged spies is an indication of a proxy war between the neighbors over Syria.
"It has to do with Syria. It is all tying to the large sectarian warfare that has started in our region," said Aydintasbas. "Turkey supporting the rebels in Syria, and Iranians are retaliating by giving tacit clandestine support to the PKK, allowing them to operate out of their territory, turning a blind eye and at times letting them carry over weapons over areas they control into Turkish territory. So the background is the big Turkish - Iranian rivalry, read Sunni - Shia rivalry."
Ankara had seen Tehran as a partner in its battle against the PKK. Last month the Turkish deputy prime minister, Bulent Arinc, admitted that sensitive intelligence information gathered by U.S. surveillance drones on rebel activities had been passed to Iranian security forces.
Until the Syrian crisis, the neighbors were close allies. But Suat Kiniklioglu, director of the Istanbul-based research group Stratim and former member of parliament, says the spying allegations against Tehran will have consequences.
"This is obviously a source for serious concern and I think there has been a source of unwarranted optimism about the relationship and I think that is now being corrected," said Kiniklioglu.
While Turkey's population is predominantly Sunni, there are some followers of the Shi'ite faith known in Turkey as Ja'faris, the same branch of the Islamic faith as predominantly Shi'ite Iran.
According to columnist Balci of Zaman, the growing numbers of converts to Shi'ism in Turkey could attract the attention of Turkish security forces in the light of the Iranian spy scandal.
"Their numbers are growing day by day," said Balci. "If this conversion is accompanied by espionage links it becomes a problem. Out of the nine people who were arrested, six of them were Turkish citizens who were Ja'fari. This conversion becomes problematic because it is accompanied a political project of Iran."
Soli Ozel, a teacher of International relations at Istanbul's Kadir Has University, worries that the Iranian spying scandal is adding to increasing sectarianism in Turkey's Islamic media.
"They can only see the world either though Islamism or Sunni - Shia divisions, and I don't think is going to get us far," said Ozel. "I don't think this is getting us to a good place, and this is a way actually to analyze the world. And it is very, very dangerous for Turkey to be caught in that sectarian discourse."
Turkish Prime Minister Recep Tayyip Erdogan is being accused of increasingly using sectarian language and taking a pro-Sunni stance over Syria, something he denies.