Turkish president Recep Tayyip Erdogan has called on Saudi Arabia to reveal who ordered the killing of journalist Jamal Khashoggi, piling further pressure on the country’s embattled crown prince.

Mr Erdogan called Saudi explanations for Khashoggi’s death “childish” in a speech to members of his Justice and Development (AK) Party in Ankara on Friday, and promised to reveal more details of the Turkish investigation soon.

“Who gave the order for 15 people to come to Turkey?” he said, referring to the Saudi security team alleged to have been sent to Istanbul to carry out the killing.

Addressing another key unanswered question in the case, Mr Erdogan called for the Saudis to produce Mr Khashoggi’s body. “It is crystal clear that he is murdered but where is the body? You have to show it,” he said.

His comments mark an escalation in a row between Turkey and its regional rival over the killing of the dissident journalist, which has plunged the Saudi royal family into crisis and angered even its closest allies.

On Thursday, following weeks of shifting statements, Saudi prosecutors concluded that the killing of Mr Khashoggi was premeditated, arriving at the same conclusion that Turkish investigators reached in the days after his disappearance.

The attempted cover-up has strained already poor relations between Mr Erdogan and the powerful Crown Prince Mohammed bin Salman, Saudi Arabia’s de-facto leader.

Originally written-off as a “rogue operation”, the crisis has made its way to the palace gates, with members of the crown prince’s own security team named as suspects by Turkish officials. Saudi Arabia has repeatedly denied any suggestion that the crown prince had knowledge of the killing.

Saudi authorities have arrested 18 people in connection to the killing, but nothing has been heard from them since, a development that has frustrated Ankara. Seemingly addressing the crown prince on Friday, Mr Erdogan called for those suspects to be returned to Turkey to “eliminate suspicion”.

He said: “You know how to make people talk. But if you cannot make them talk, then hand them over to us. This incident happened in Istanbul. Let us put them on trial.”

Just hours later, Turkey’s state-run news agency said prosecutors would be formally requesting that the 18 suspects be extradited.

Jamal Khashoggi death: key figures Show all 7 1 /7 Jamal Khashoggi death: key figures Jamal Khashoggi death: key figures Jamal Khashoggi Washington Post journalist who was critical of the Saudi regime and the young Crown Prince Mohammed bin Salman, he was murdered on 2 October in the Saudi Arabian consulate in Istanbul AFP Jamal Khashoggi death: key figures Saudi Crown Prince Mohammed bin Salman Heir to the Saudi throne, Mohammed bin Salman has been implicated in the murder, with US officials claiming that he must have known of the plot AFP/Getty Jamal Khashoggi death: key figures 15 man hit squad Turkish police suspect these 15 men of being involved in the murder of Jamal Khashoggi, issued 10 October, 8 days after the journalist disappeared EPA Jamal Khashoggi death: key figures Saud al-Qahtani Aide to Crown Prince Mohammed bin Salman, Saud al-Qahtani is claimed to have ordered Khashoggi's murder Saud Al-Qahtani/Twitter Jamal Khashoggi death: key figures Maher Abdulaziz Mutreb A former diplomat who often travelled with the Crown Prince, Mutreb was initially claimed to be the leader of the hit squad and is pictured here entering the Saudi consulate on the day of the murder AP Jamal Khashoggi death: key figures Mustafa al-Madani First implicated in the 15 CCTV photos released by the Turkish police, al-Madani was later found to have been used as a body double for Khashoggi, leaving the Saudi consulate dressed in his clothes on the day the journalist was killed CNN Jamal Khashoggi death: key figures Salah bin Jamal Khashoggi (L) Son of the murdered journalist met with Crown Prince Mohammed bin Salman on 23 October EPA

“Jamal Khashoggi was murdered in Turkey by Saudi nationals who travelled to Turkey for this specific purpose,” a senior Turkish official said. “It is clear that the judicial system in Turkey is better equipped to genuinely serve the cause of justice in this case.”

The killing of Mr Khashoggi, a columnist for The Washington Post who was critical of Crown Prince Mohammed’s crackdown on dissent, was all the more shocking to many because it took place in Turkey, a place that dissidents from across the Arab world considered a safe haven.

Mr Khashoggi’s fiancee, Hatice Cengiz, who waited outside the consulate for her partner for hours when he did not emerge on 2 October, said Mr Khashoggi had believed Saudi officials would not be so bold as to harm him in Turkey.

“He thought Turkey is a safe country and if he would be held or interrogated, this issue would be swiftly solved,” she said in an interview with Turkish broadcaster Haberturk on Friday.

The Saudi royal family has strenuously denied any involvement in Mr Khashoggi’s death. At a conference in Riyadh on Wednesday, the crown prince said the killing was a “heinous crime that cannot be justified” and warned against any efforts to “manipulate” the crisis and drive a wedge between Saudi Arabia and Turkey.

Donald Trump: Jamal Khashoggi death 'the worst cover up ever'

But analysts said that by attacking the Saudi leadership for a second time this week, Mr Erdogan has sent a message that he is unmoved by the crown prince’s overtures, and may seek to use the tragedy to gain leverage over his rival.

“As long as this Khashoggi affair is on the agenda, Erdogan wins,” Turkish journalist Ilhan Tanir told The Independent.

“Even before this happened, Mr Erdogan and the young prince were not getting along, and everything appeared to be running against Mr Erdogan. Now he is driving a wedge between the US and Saudis and capturing the attention of the entire national media, which he loves.”

Mr Khashoggi’s killing has shone a spotlight on the west’s relationship with Saudi Arabia. Even as thousands of civilians have been killed by US and UK-made weapons in a Saudi-led campaign in Yemen over the past three years, arms sales have continued apace.

But those lucrative deals are facing fresh scrutiny. This week, the European parliament voted in a non-binding resolution for an EU-wide arms embargo on Saudi Arabia.

French president Emmanuel Macron dismissed the calls as “demagoguery” on Friday, saying weapons sales had “nothing to do with Mr Khashoggi”.

The largest arms suppliers to Saudi Arabia – the US and the UK – have also refused to consider a halt to sales.

Since Saudi Arabia intervened in Yemen in 2015 to reinstall the internationally recognised government of president Abdu Rabbo Mansour Hadi, UK arms exporters have earned £4.6bn from sales to the Saudi regime. Foreign secretary Jeremy Hunt has emphasised that the UK’s “strategic” relationship would be measured against any response.

US president Donald Trump described the Saudi actions in the aftermath of Mr Khashoggi’s disappearance as “one of the worst cover-ups in the history of cover-ups” and has suggested the crown prince may have been involved. But he also said he did not want to lose the massive profits made from selling weapons to the Saudi military.

Mr Trump’s position has hardened over time, however, and may do so further as more details of the killing emerge. CIA director Gina Haspel was in Turkey earlier this week to review evidence, and was reportedly played audio tapes of the killing. She returned to Washington on Thursday to brief the president.

So far, only Germany has taken concrete steps to target the Saudi state. “It is necessary to clarify the background of this horrible incident,” chancellor Angela Merkel said in Prague during a news conference with Czech prime minister Andrej Babis.

Meanwhile, the investigation into Mr Khashoggi’s death has shown no signs of slowing down. The pro-government newspaper Sabah said 3,500 hours of recordings have been examined so far and a team of 750 people has been formed to investigate the murder.