Istanbul, Oct 6 (AFP) A Saudi columnist remained missing as supporters rallied outside the Saudi consulate in Istanbul calling for his "release" despite Riyadh's denials that he was being held there.

Jamal Khashoggi, a contributor to the Washington Post, has not been seen since he went to the Saudi mission on Tuesday to receive an official document for his marriage.

The Turkish-Arab Media Association (TAM) organised a rally in front of the consulate for Khashoggi, a former government adviser who has been critical of some policies of Saudi Crown Prince Mohammed bin Salman and Riyadh's intervention in the war in Yemen.

He has lived in self-imposed exile in the United States since last year to avoid possible arrest.

The crown prince told Bloomberg that the journalist was not inside the consulate and said he was ready to allow Turkish authorities to search the building.

"We are ready to welcome the Turkish government to go and search our premises," he said, which is Saudi sovereign territory.

He added, "We will allow them to enter and search and do whatever they want to do... We have nothing to hide," he said in the interview published on Friday.

According to Khashoggi's fiancee, a Turkish woman called Hatice A., he went to the consulate and never re-emerged.

Ankara and Riyadh have given contradictory versions of the circumstances of Khashoggi's disappearance, with Turkish officials saying they believed he was still inside the consultate.

But Saudi Arabia claimed he had entered and then left the mission on Tuesday.

"As journalists we are concerned by the fate of Jamal. We do not know if he is alive or not, and the statements by Saudi Arabia on the subject are far from satisfactory," Turan Kislakci, a friend of Khashoggi and TAM chief, said in a statement to supporters.

As Kislakci spoke, supporters held up images of the journalist, with the words "Free Jamal Khashoggi".

"We believe that Jamal Khashoggi is the consulate's 'host' and call for his immediate release, or to tell us where he is," Kislakci added.

Lynn Maalouf, Amnesty International's Middle East research director, urged Riyadh to "immediately disclose the evidence supporting their claim" that he left the consulate, "otherwise their claims are utterly baseless".

Yemeni activist and 2011 winner of the Nobel Peace Prize, Tawakkol Karman, hit out at the Saudi authorities and told AFP that she believed Khashoggi "was kidnapped in this gangster's den that is supposed to be a consulate".

"What we want is Jamal Khashoggi's release. He entered the building of the consulate, he has to come out of there safe and sound. And the Turkish government must assume its role and deal with the case of Jamal Khashoggi because Turkish sovereignty has been violated," she added.

Human Rights Watch called on Ankara to "deepen their investigation" into the journalist's whereabouts, saying his possible detention could "constitute an enforced disappearance" in a statement late Thursday.

"If Saudi authorities surreptitiously detained Khashoggi it would be yet another escalation of Crown Prince Muhammad bin Salman's reign of repression against peaceful dissidents and critics," Sarah Leah Whitson, Middle East director at HRW, said.

Amnesty's Maalouf said the incident "sends a petrifying signal" to the kingdom's critics and dissidents. (AFP) DIP

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