In a speech to parliament about a case that has sparked outrage around the globe, Erdogan did not mention Crown Prince Mohammed bin Salman, who some U.S. lawmakers suspect ordered the killing.

But he said Turkey would not complete its investigation into Khashoggi's death until all questions were answered and Turkey was told the identity of a local collaborator Riyadh says disposed of the body.

Read: Saudi Arabia Admits Khashoggi Died in Consulate

"Intelligence and security institutions have evidence showing the murder was planned. Pinning such a case on some security and intelligence members will not satisfy us or the international community," he said.

"The Saudi administration has taken an important step by admitting to the murder. From now on, we expect them to uncover all those responsible for this matter from top to bottom and make them face the necessary punishments," he said.

"From the person who gave the order, to the person who carried it out, they must all be brought to account."

A Saudi cabinet meeting chaired by King Salman said Riyadh would hold to account those responsible for the killing and those who failed in their duties, whoever they were.

Read: Saudi Calls Khashoggi Killing Grave Mistake

Erdogan said the whereabouts of Khashoggi'sbodywere still unknown and he demanded Saudi Arabia reveal the identity of a "local cooperator" who purportedly took the body.

Erdogan's speech coincided with the opening in Riyadh of an investment conference which Western political figures, leading international bankers and company executives have boycotted because of the furor around Khashoggi's death.

The Washington Post columnist, a sharp critic of the crown prince, the kingdom's de facto ruler, disappeared three weeks ago after entering the Saudi consulate in Istanbul to obtain documents for his upcoming marriage.

REUTERS