Istanbul, Turkey (CNN) Jamal Khashoggi died as a result of a brutal premeditated murder, Turkey's President Recep Tayyip Erdogan said on Tuesday, in a highly anticipated speech in which he soundly rejected Saudi Arabia's claim that the journalist was killed accidentally.

Erdogan questioned whether Riyadh was able to carry out an independent investigation in to the death of the Washington Post journalist, and he demanded that the 18 suspects arrested by authorities in Saudi Arabia be extradited to Turkey to stand trial in Istanbul.

It was the first time that any official in Turkey has publicly outlined the Turkish contention that Khashoggi was killed at Saudi Arabia's consulate in Istanbul by a hit squad sent from Riyadh. While Erdogan did not offer any bombshell revelations, his speech amounted to a comprehensive rejection of Saudi Arabia's case that Khashoggi died by accident as a result of a brawl.

People gather around a TV at an Istanbul cafe to watch Erdogan's speech.

"The information obtained so far and the evidence found shows that Khashoggi was murdered in a ferocious manner," Erdogan told lawmakers in the Turkish capital, Ankara.

Among the new details revealed by Erdogan was an allegation that, on the day before Khashoggi was killed, a team of consular staff carried out a reconnaissance mission in a forest on the outskirts of Istanbul, and at Yalova, a city about a 55-mile (90-kilometer) drive south. Erdogan did not say why the locations were scouted, but he noted later that Khashoggi's body has yet to be found.

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