The Turkish president, Recep Tayyip Erdoğan, has publicly torn down Saudi claims that the dissident journalist Jamal Khashoggi died in a fight in its Istanbul consulate, making fresh allegations that his “savage” murder was premeditated and calling for an independent investigation in Turkey.

Erdoğan had billed his keenly awaited address at the Turkish parliament in Ankara as the moment he would reveal the “naked truth” about what happened to Khashoggi. He said he was not satisfied with Riyadh’s suggestion that the killing was a rogue extradition operation gone wrong, and called for the “highest ranked” of those responsible to be brought to justice.

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

Contrary to expectations, Erdoğan’s first update on the three-week-old case did not officially reveal the existence of audio and video evidence understood to be in Turkey’s possession.

Erdoğan did reveal that on the day before Khashoggi was killed, Saudi agents arrived in Istanbul and began to scout locations, including the Belgrad forest near Istanbul and the city of Yalova to its south. Police have subsequently searched both areas for Khashoggi’s remains.

The president did not name the powerful Saudi crown prince Mohammed bin Salman, the kingdom’s de facto ruler who, it is alleged, was probably aware of, and possibly even ordered, the silencing of his prominent critic, but observers were in little doubt to whom his repeated mentions of “highest ranked” referred.

He otherwise spoke of the “sincerity” of Saudi Arabia’s King Salman in the investigation. The gaps in the speech suggested Erdoğan has more cards to play in the evolving diplomatic crisis.

Erdoğan’s speech came as the Saudi foreign ministry released extraordinary photos of Khashoggi’s son, Salah bin Jamal Khashoggi, meeting the crown prince and king in Riyadh on Tuesday.

Facebook Twitter Pinterest Salah bin Jamal Khashoggi shakes hands with Crown Prince Mohammed bin Salman on Tuesday. Photograph: Ministry of foreign affairs of Saudi Arabia

Saudi Arabia’s widely derided version of events has created a scandal for the kingdom. The G7 industrialised nations issued a fresh call for “a thorough, credible, transparent and prompt investigation”, adding Saudi Arabia needed to put in place “measures to ensure that something like this cannot happen again”.

Donald Trump said the apparent murder plot was a “terrible thing”, telling reporters on Tuesday “they had a very bad original concept, it was carried out poorly and the cover-up was the worst in the history of cover-ups. They had the worst cover-up ever.”

Shortly afterwards, the US secretary of state, Mike Pompeo, said the US would revoke the visas of Saudi officials implicated in Khashoggi’s death, and was exploring using sanctions against them. Any such move would be the first punitive measures taken by the Trump administration since Khashoggi disappeared.

Many western firms have pulled out of a large foreign investment conference in Riyadh that began on Tuesday.

On the ground in Istanbul on Tuesday, police told Turkish television that they had been allowed to search a diplomatic car belonging to the Saudi consulate in the presence of Saudi investigators. Two suitcases containing documents and a laptop had been retrieved from the vehicle, although it was not immediately clear who they belonged to.

Khashoggi did not appear to be carrying any belongings when he entered the consulate the day he died, and electronics are not allowed inside the building.

Surveillance footage shows that the car, found in an underground car park in Sultangazi district on Monday, was approached by a man who retrieved a package from the boot several days ago.

Tabling the new allegations that Saudi officials scoped out rural areas outside Istanbul the day before Khashoggi’s murder, Erdoğan said in his address that Turkey’s investigation was ongoing.

“Saudi Arabia has taken an important step by admitting the murder,” Erdoğan said. “As of now, we expect of them to openly bring to light those responsible – from the highest ranked to the lowest – and to bring them to justice.”

He said Saudi Arabia must relinquish control of the investigation into the “political” murder to an independent and unbiased Turkish operation in Istanbul.

The president strongly criticised Saudi Arabia’s “inconsistent statements” in the case and demanded the kingdom identify the “local collaborator” who allegedly disposed of Khashoggi’s body.

Riyadh says Khashoggi was accidentally choked during a rendition attempt that went wrong, and his body was rolled up in a rug and given to a third party.

Turkish investigators, however, have steadily leaked evidence to the media that allegedly proves the journalist was tortured, murdered and his body dismembered within the consulate building. CCTV footage shows a body double dressed in Khashoggi’s clothes leaving the consulate and touring Istanbul’s landmarks, undermining the idea that the team interrogating Khashoggi meant to bring him back alive.

Play Video 1:01 Jamal Khashoggi: surveillance footage shows 'body double' – video

As reported by the Observer on Sunday, Turkish investigators may have intercepted the hit squad’s communications. Reuters said on Monday that Saud al-Qahtani, an influential adviser to Bin Salman, participated in a Skype call to the room in the consulate where Khashoggi was held, telling the team to “bring me the head of the dog”.

Khashoggi case has put Saudi prince right where Erdoğan wants him Read more

Qahtani and several other senior officials have been fired from their government positions. Erdoğan said that of the 18 men arrested by Saudi Arabia in the investigation, 15 were those already identified by Turkish police as members of the hit squad who flew in and out of Istanbul on the same day Khashoggi was killed. The suspects should be extradited immediately to assist with the Turkish investigation, he said.

Other parties, such as Khashoggi’s family, have requested a United Nations inquiry.