Turkish security forces launched operations on the Air Force Academy in Istanbul early Monday, in relation to the failed coup attempt by the Gülenist Terror Organization (FETÖ).

According to reports, Istanbul counter-terror units raided the academy located in Istanbul's Yeşilköy district.The 10th Air Tanker Base in Adana's Incirlik Air Base was also searched Monday in connection with Friday's failed coup attempt.

Police are investigating air traffic control and radar data at the base from where a tanker aircraft which refueled warplanes involved in bombing Ankara during Friday's coup were found to have taken off.

Speaking on condition of anonymity due to restrictions on talking to the media, the sources added that the military crew which enabled the refueling of the F-16s is also under investigation. Two acting Chief Public Prosecutors and five prosecutors from Adana Chief Public Prosecutor's Office are in charge of the investigation.

The deadly coup attempt happened late Friday when rogue elements of the Turkish military attempted to overthrow the country's democratically elected government.

At least 208 people, including members of the security forces and civilians, were killed in Istanbul and Ankara and nearly 1,500 others were wounded as they protested against the coup.

The government has said the attempted coup was organized by followers of U.S.-based preacher Fetullah Gülen, who is accused of a long-running campaign to overthrow the state through supporters within Turkish institutions, particularly the military, police and judiciary, forming a so-called 'parallel state'.