Footage has surfaced in Turkish media showing an alleged 15-member Saudi "assassination squad" making suspicious movements at the Saudi Consulate in Istanbul where journalist Jamal Khashoggi disappeared a week ago.

Key points: Images and video of alleged hit squad flood Turkish media

Images and video of alleged hit squad flood Turkish media Sources say a special team was ordered in by highest level of Saudi court

Sources say a special team was ordered in by highest level of Saudi court Trump says he will raise missing journalist with Saudi Arabia

It comes as The New York Times reports that highly placed Turkish security sources told the publication that Khashoggi was killed within hours of entering the consulate by a special hit squad on the orders of the Saudi government and that his body had been dismembered with a bone saw.

"It is like Pulp Fiction," one official told the Times.

Saudi Arabia has remained silent as the images have played across television networks in Turkey and around the world.

CCTV images show the Saudi hit men allegedly involved in Khashoggi's disappearance. ( Reuters: TRT World )

Turkish officials fear the team killed Khashoggi, who has been critical of Saudi Crown Prince Mohammed bin Salman in his writing.

The kingdom has dismissed the allegation as "baseless", but has released no evidence supporting its version of events which is that Khashoggi left the consulate unharmed shortly after entering.

Turkish media awash with images, video and theories

The Saudi government has denied the allegations, but not provided any evidence. ( AP: Lefteris Pitarakis )

State-run broadcaster TRT aired video purportedly showing the Saudis arriving by private jet and then leaving a hotel.

The footage shows Khashoggi entering the consulate on October 2. An hour and 54 minutes later, according to the time stamp, a black Mercedes Vito with diplomatic license plates, which resembled a van parked outside of the consulate when the writer walked in, drives some 2 kilometres to the consul's home, where it parks inside a garage.

The footage all seemed to come from surveillance cameras, which would have been posted throughout the district housing the Saudi consulate and other diplomatic missions. No one has produced any such footage of Khashoggi leaving the consulate.

The Sabah newspaper, which is close to Turkish President Recep Tayyip Erdogan, published images of what it referred to as the "assassination squad" apparently taken at passport control. It said they checked into two hotels in Istanbul on October 2 and left later that day.

One of the 15 Saudis identified by name and photo in the Sabah report is a forensic expert who has worked at the Saudi Interior Ministry for 20 years, according to a LinkedIn profile and Saudi media, and serves on the board of the Saudi Society of Forensic Medicine.

Other names and photos of the 15, who Sabah said travelled on diplomatic passports, match officers in the Saudi Army and Air Force, as identified by previous Saudi media reports and in one case a Facebook profile.

Trump demands answers as US launches investigation

Turkish officials say they believe Jamal Khashoggi was killed inside the Saudi consulate in Istanbul. ( AP: Hasan Jamali, file )

Khashoggi had written a series of columns for the Washington Post that were critical of Saudi Arabia's assertive Prince Mohammed, who has led a widely publicised drive to reform the conservative Sunni monarchy but has also presided over the arrests of activists and businessmen.

Mr Erdogan has not accused Saudi Arabia of being responsible for Khashoggi's disappearance but has said that if the Saudis have footage of him leaving the consulate they should release it.

Saudi Arabia is a major investor in Turkey, despite Ankara's support for the Gulf nation of Qatar, which is under a blockade led by Saudi Arabia and three other Arab nations.

On Wednesday, the Post published a column by Khashoggi's fiancée, Hatice Cengiz. She said the writer first visited the consulate on September 28 "despite being somewhat concerned that he could be in danger".

He later returned October 2 after being promised the necessary paperwork so the two could be married.

"At this time, I implore President Trump and first lady Melania Trump to help shed light on Jamal's disappearance," Ms Cengiz wrote.

Sorry, this video has expired Khashoggi's colleague pleads for Trump to demand answers from Saudi Arabia

Khashoggi's colleague and Global Opinions Editor of The Washington Post Karen Attiah also called on Mr Trump to seek answers from Saudi Arabia.

"I would like him to say that attacking or detaining or murdering a US resident, someone who lived in Virginia, someone who is a writer for The Washington Post, is unacceptable, beyond condemnation," Ms Attiah said through tears.

"If whoever did this could get away with silencing him, just imagine all the other journalists … people are calling me asking 'am I next?'"

Sorry, this video has expired Donald Trump "demanding" answers from Saudi Arabia on Jamal Khashoggi

Mr Trump, who took his first overseas trip as US President to the kingdom and whose son-in-law Jared Kushner has close ties to Prince Mohammed, said he had raised Khashoggi's case with Saudi Arabia "at the highest level" and more than once in recent days.

"We're demanding everything," Mr Trump said when asked if he was demanding information from the Saudis.

"People saw him go in and didn't see him come out. We're going to take a very serious look at it. It's a terrible thing … this is a bad situation. We cannot let this happen, to reporters, to anybody."

Politicians in the US, Riyadh's main ally, have warned that any harm done to the Washington Post contributor will jeopardise America's relations with the world's largest oil exporter.

Earlier, a bipartisan group of US senators triggered an investigation into Khashoggi's disappearance to determine whether "a foreign person is responsible for an extrajudicial killing, torture, or other gross violation of internationally recognised human rights."

They are expecting a report on who was responsible within 120 days.

A security guard closes the entrance to a blocked road leading to the Saudi consulate in Istanbul. ( AP: Emrah Gurel )

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