He said Turkey had strong evidence Khashoggi was killed in a premeditated and “savage” murder at the Saudi consulate in Istanbul on 2 October.
He also called for the suspects to be tried in Istanbul.
He demanded Saudi Arabia provide answers about where Khashoggi’s body was, and who ordered the operation.
The Saudi kingdom has provided conflicting accounts of what happened to the Washington Post contributor. After weeks of maintaining he was still alive, the authorities now say the fifty-nine-year-old was killed in a rogue operation.
Tuesday’s address by President Erdogan coincided with the start of an investment conference in Saudi Arabia that has been overshadowed by the Khashoggi case, with dozens of government and business leaders pulling out.