While Donald Trump was telling reporters he believed that missing Saudi journalist Jamal Khashoggi is dead, investigators were said to be searching wooded areas near Istanbul for possible remains of the dissident.

Local media reported that the investigation into Mr Khashoggi's disappearance from his nation’s consulate in Istanbul more than two weeks ago has moved beyond the city to its rural outskirts.

Turkish broadcast and print news outlets reported that police had used surveillance camera footage had traced vehicles that crossed paths with 15 alleged Saudi operatives who arrived in Istanbul from Riyadh shortly before Mr Khashoggi’s disappearance to Belgrade Forest, a large park on the city’s northern outskirts, and to farmlands in Yalova Province about 50 miles from Istanbul. Earlier on Thursday, Turkish media also published new images of one of the men alleged to be been part of the 15-person team, who Turkish officials believe murdered Mr Khashoggi.

Citing Turkish security sources, Qatar-based Al Jazeera aired a report saying six cars departed from the consulate the evening of his disappearance in a possible attempt to confuse officials. The channel said police believe Mr Khashoggi's body could be buried at sites where diplomatic cars visited the night he disappeared. “Police are searching locations in the Belgrad Forest, the Beykent area and the nearby Yalova area. Police believe these areas are linked to Khashoggi's disappearance,” it added.

On his way to a campaign rally in Montana, Mr Trump said it "certainly looks" as though Mr Khashoggi is dead.

“It certainly looks that way to me,” Mr Trump said as he departed for Missoula. “It's very sad. Certainly looks that way.”

Khashoggi disappearance: Forensic police investigate Saudi consul Show all 12 1 /12 Khashoggi disappearance: Forensic police investigate Saudi consul Khashoggi disappearance: Forensic police investigate Saudi consul According to local media reports, Saudi consul Mohammad al-Otaibi left Turkey on 16 October. A Turkish prosecutor on 15 October has entered the Saudi consulate in Istanbul to investigate the disappearance of dissident Saudi journalist Jamal Khashoggi, an inspection that was being carried out jointly with a Saudi team AFP/Getty Images Khashoggi disappearance: Forensic police investigate Saudi consul Turkish forensic police officers work on the roof of the residence of the Saudi consul in Istanbul EPA Khashoggi disappearance: Forensic police investigate Saudi consul Khashoggi went missing on 2 October when he entered the Saudi consulate to pick up paperwork AP Khashoggi disappearance: Forensic police investigate Saudi consul ISTANBUL, TURKEY - OCTOBER 17: Turkish police arrive to investigate the Saudi Arabian consulate general residence as investigations continue into the disappearance of journalist Jamal Khashoggi on October 17, 2018 in Istanbul, Turkey. Turkish police first entered and searched the Saudi Arabian consulate on October 15 amid a growing international backlash about the disappearance. Khashoggi, a U.S. resident and critic of the Saudi regime, has been missing since visiting the Saudi Arabian consulate on October 2. Turkish officials have said they believe he was killed inside. (Photo by Chris McGrath/Getty Images) ***BESTPIX*** Chris McGrath Khashoggi disappearance: Forensic police investigate Saudi consul Turkish forensic and investigation officers arrive at Saudi Consul's residence on October 17, 2018 in Istanbul. - Saudi Arabia's consul to Istanbul Mohammed al-Otaibion on October 16, 2018 left the Turkish city bound for Riyadh on a scheduled flight, reports said, as Turkey prepared to search his residence in the probe into the disappearance of journalist Jamal Khashoggi. (Photo by OZAN KOSE / AFP)OZAN KOSE/AFP/Getty Images OZAN KOSE AFP/Getty Images Khashoggi disappearance: Forensic police investigate Saudi consul Turkish police arrive to investigate the Saudi Arabian consulate general residence Getty Images Khashoggi disappearance: Forensic police investigate Saudi consul Turkish forensic police search for evidence at the garden of the Saudi Arabia's Consul General Mohammad al-Otaibi AFP/Getty Images Khashoggi disappearance: Forensic police investigate Saudi consul Turkish police search the rooftop of the Saudi Arabian consulate general residence Getty Images Khashoggi disappearance: Forensic police investigate Saudi consul Turkish police arrive at the residence of the Saudi consul General Mohammed al-Otaibi to conduct a search AP Khashoggi disappearance: Forensic police investigate Saudi consul Turkish police officers gather as they prepare to enter Saudi Arabia consul's residence, in Istanbul, Wednesday, Oct. 17, 2018. America's top diplomat is in Turkey, where a strongly pro-government newspaper has published a gruesome recounting of the alleged slaying of Saudi writer Jamal Khashoggi at the Saudi Consulate in Istanbul. (AP Photo/Petros Giannakouris) Petros Giannakouris AP Khashoggi disappearance: Forensic police investigate Saudi consul Turkish forensic police search for evidence at the garden of the Saudi Arabia's Consul General Mohammad al-Otaibi AFP/Getty Images Khashoggi disappearance: Forensic police investigate Saudi consul ISTANBUL, TURKEY - OCTOBER 17: Turkish police search the rooftop of the Saudi Arabian consulate general residence as investigations continue into the disappearance of journalist Jamal Khashoggi on October 17, 2018 in Istanbul, Turkey. Turkish police first entered and searched the Saudi Arabian consulate on October 15 amid a growing international backlash about the disappearance. Khashoggi, a U.S. resident and critic of the Saudi regime, has been missing since visiting the Saudi Arabian consulate on October 2. Turkish officials have said they believe he was killed inside. (Photo by Chris McGrath/Getty Images) Chris McGrath Getty Images

While US officials are awaiting the results of a joint Saudi-Turkish investigation, the president said he feels confident "we should be able to get to the bottom fairly soon". He added that he would consider "severe" consequences if Saudi Arabia was involved. Earlier in the day Secretary of State Mike Pompeo had told Mr Trump Saudi Arabia needs a "few more days" to complete their investigation.

Saudi officials have repeatedly denied any involvement in the disappearance of the journalist. State-directed Saudi press and pro-Saudi social media accounts have described the group of 15 as “tourists” and has doubled down on its denials, despite reports Saudi Arabia might pin the killing on low-ranking officials. “The kingdom is more powerful than enemies’ conspiracies,” read a headline in pro-government Okaz newspaper. “No to threats, no to blackmailing, no to pressure”

Turkish justice minister Abdulhamit Gul told the official Anatolia News Agency Mr Khashoggi’s disappearance was being investigated thoroughly by the Istanbul prosecutors office and insisted that “results are expected to come out soon.”

Jamal Khashoggi: Everything we know

Earlier on Thursday, a team of groggy crime scene investigators in hazmat suits could be seen leaving the compound of the Saudi consul general after a nine-hour search of the premises. A team of 15 alleged Saudi operatives apparently jetted into Istanbul from Riyadh hours before Mr Khashoggi’s scheduled 2 October arrival at the consulate and subsequent disappearance, stopping off at the consul general’s residence for two hours before heading back to the airport.

The Turkish daily Sabah newspaper published new surveillance camera stills of one of those men, Maher Abdulaziz Mutreb, who had been exposed by The New York Times this week as a frequent presence in Saudi Crown Prince Mohammed bin Salman’s entourage.

The fresh images showed Mr Mutreb arriving at the consulate shortly before 10am on 2 October, leaving the consul-general’s residence shortly before 5pm, and checking out of his hotel a few minutes later, in the presence of a large suitcase, before being spotted at Istanbul’s Ataturk Airport heading out of the country just before 6pm.

A number of nations, including the UK, have called for clarity from Saudi Arabia over the crisis. On Thursday, the UK International Trade Secretary Liam Fox was one of a number of officials to pull out of an international investor conference in Riyadh. A Government spokesman said Dr Fox had decided the “time is not right” for him to attend the Future Investment Initiative in Riyadh later this month.

“The UK remains very concerned about Jamal Khashoggi's disappearance,” the spokesman said.

French finance minister Bruno Le Maire and his Dutch counterpart Wopke Hoekstra also announced they were pulling out of the event dubbed “Davos in the desert”. US Treasury Secretary Steven Mnuchin later joined them in withdrawing, following a meeting with Mr Trump.

US Vice President Mike Pence made clear what the international commuity expects during a stop in Denver earlier in the day, vowing: "the world deserves answers."

Mike Pompeo: the Saudis should be provided “a few more days” to complete their investigation into the disappearance of Jamal Khashoggi

The alleged killing of Mr Khashoggi has also rattled dissident journalists and activists worldwide, and sparked fears of a wave of impunity. The Soufan Centre, an intelligence consultancy, warned of a wave of state-sponsored killings of political enemies that could increase if there are no consequences if Saudi Arabia is found to be involved.

“The clear evidence and resulting outrage so far haven’t produced much in terms of changing behaviours of governments like Russia, North Korea, and now Saudi Arabia,” it said. “A tepid international response will likely encourage future similar behaviours and even inspire other rogue actors to follow suit.”

The steady flow of leaks has kept the Khashoggi affair high on the global news agenda but also added to confusion to the case. On Thursday four major US and European human rights and press freedom organisations, alarmed by signs of backroom dealmaking by world powers, called for a United Nations probe into the disappearance of Mr Khashoggi.

The groups, which include Amnesty International, Human Rights Watch, Reporters Without Borders, and the Committee to Protect Journalists, at a press conference in New York called on Turkey to ask UN Secretary-General Antonio Guterres to launch an investigation to determine who ordered, planned, and carried out what unnamed Turkish and US officials have described to journalists as the extrajudicial killing of Mr Khashoggi.

“Turkey should enlist the UN to initiate a timely, credible, and transparent investigation” Robert Mahoney, deputy executive director of the Committee to Protect Journalists, said in a joint statement released. “UN involvement is the best guarantee against a Saudi whitewash or attempts by other governments to sweep the issue under the carpet to preserve lucrative business ties with Riyadh.”

The call came amid alarm among the rights groups over a recent swirl of backroom diplomatic meetings between top-ranking US, Saudi, and Turkish officials and worries by some that justice for Mr Khashoggi could be undermined by geopolitical machinations. The US needs Saudi oil, Saudi Arabia needs US military supplies and protection, Turkey needs the help and cooperation of both to fix up its ailing economy and protect its southern border from the chaos in neighbouring Syria.

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“This is exactly why this call is a no-brainer,” Sherine Tadros, head of Amnesty International's New York office, told The Independent. “You have the Secretary General of the UN saying we need to know the truth. You have President Trump saying Saudi is being treated as guilty until proven innocent. The only chance we have to have an investigation that could possibly not be politicised, is to do it through the UN.”

The UN has been approached about the idea and begun to warm to it, said a source. A statement by the Istanbul prosecutor’s office on Thursday said Turkey’s investigation complies with international law and standards.

The four rights organisations urged Saudi to waive diplomatic protections and grant access to officials and Turkey to hand over any audio and visual evidence to a UN investigative team to interview witnesses and collect and preserve any evidence for future prosecutions, and recommend venues for pursuing justice. They urged using as a model the probe into the assassination of former Pakistani Prime Minister Benazir Bhutto, which was undertaken by the UN at the request of Islamabad.