Riyadh (AFP) - "Rogue killers" could be to blame for the disappearance of Saudi journalist Jamal Khashoggi, US President Donald Trump has said, as his Secretary of State headed to Riyadh in an attempt to find out what happened.
Turkish police on Monday searched the Saudi consulate in Istanbul for the first time since Khashoggi, a Saudi national and US resident who became increasingly critical of powerful Crown Prince Mohammed bin Salman, went missing.
He has not been seen since he walked into the Istanbul consulate to sort out marriage paperwork on October 2.
Turkish officials have said they believe he was killed -- a claim Saudi Arabia has denied -- with the controversy dealing a huge blow to the kingdom's image and efforts by its youthful crown prince to showcase a reform drive.
But US media reported on Monday that the kingdom is considering an admission that Khashoggi died after an interrogation that went wrong during an intended abduction.
Trump dispatched Secretary of State Mike Pompeo for what the State Department described as "face to face meetings with the Saudi leadership".
Until now, Riyadh has not allowed Turkish investigators to search the consulate -- officially Saudi territory -- with reports both sides were at odds over the conditions.
The team, which arrived in a motorcade of six cars late Monday, left the premises in the early hours of Tuesday after an an eight-hour search, an AFP correspondent said.
They took samples with them, including soil from the consulate garden that was loaded into vans, one official at the scene said.
A Saudi delegation had entered the consulate one hour before the Turkish police arrived and appeared still to be inside as the search was conducted.
- 'No knowledge' -
Trump's comments came after a telephone conversation with King Salman, father of the crown prince, the first such talks since the crisis erupted.
"Just spoke to the King of Saudi Arabia who denies any knowledge of whatever may have happened 'to our Saudi Arabian citizen'," Trump tweeted.
Riyadh's most recent comments have focused on having no knowledge of any killing or denying any order to kill Khashoggi had been given.
"The denial was very, very strong," Trump later told reporters at the White House. "It sounded to me like maybe these could have been rogue killers. Who knows?"
But CNN cited two sources as saying the Saudis are preparing a report that his death resulted from a botched interrogation, while the Wall Street Journal said the kingdom was weighing whether to say that rogue operatives killed Khashoggi by mistake.
After critical talks in Riyadh Tuesday, Pompeo was expected in Turkey on Wednesday to meet Turkish Foreign Minister Mevlut Cavusoglu, the state-run Anadolu news agency said.
The search came after Turkish President Recep Tayyip Erdogan and King Salman also had their first telephone talks since the controversy erupted, in what appeared to be a conciliatory conversation, according to official readouts.
While lurid claims have appeared in Turkish media -- including that Khashoggi was tortured and dismembered -- Turkey's leadership has so far refrained from pointing the finger directly at Riyadh in public comments.
King Salman emphasised the importance of the Turkey-Saudi relationship and said no one should be able to "undermine the strength of this relationship", Saudi's official media reported.
- 'Davos in Desert' unravels -
The controversy has troubled Saudi's traditional Western allies, who are key arms suppliers to the kingdom, and also undermined efforts by Mohammed bin Salman to present himself as a modernising ruler.
An investment conference seen as a platform for the crown prince and dubbed the "Davos in the Desert", which was scheduled to take place in Riyadh next week, has been hit by a string of prominent cancellations.
Business barons including British billionaire Richard Branson and Uber CEO Dara Khosrowshahi, as well as media powerhouses Bloomberg and CNN have pulled out of the Future Investment Initiative (FII).
In a major new blow for the event, JPMorgan Chase CEO Jamie Dimon and Ford chairman Bill Ford also cancelled plans to attend as well as Larry Fink, the head of investment giant BlackRock, and Steve Schwarzman of Blackstone.
US Treasury Secretary Steven Mnuchin said he still plans to attend but would "take (it)... into account" if more information came out.
Saudi stocks have also been hit, suffering days of heavy losses, but made a strong comeback on Monday with the Tadawul All-Shares Index (TASI) rising more than four percent.
Trump has threatened the kingdom with "severe punishment" if it is shown that Khashoggi was killed inside its Istanbul mission.
But he has also made clear he is reluctant to curb all-important arms sales to Saudi Arabia.
Britain, France and Germany also released a rare joint statement saying they were treating Khashoggi's disappearance "with the utmost seriousness" and calling for a "credible investigation".
Riyadh, however, has vowed to hit back against any punitive measures imposed over the affair.