(CNN) President Donald Trump vowed in a "60 Minutes" interview that the United States would get to the bottom of what happened to a missing Saudi journalist and that there would be "severe punishment" if he were found to have been killed.

In an excerpt from the interview, released by CBS on Saturday morning, Trump said the case of Jamal Khashoggi was "being looked at very, very strongly" and that his administration "would be very upset and angry" if it turned out that the Saudi government had ordered his killing.

"As of this moment, they deny it, and they deny it vehemently. Could it be them? Yes," he said in what are his strongest comments yet on the matter.

Khashoggi, a columnist for The Washington Post, went into the Saudi Consulate in Istanbul on October 2 to obtain paperwork that would allow him to marry his Turkish fiancée. He hasn't been seen in public since.

On Friday, a source familiar with the ongoing investigation told CNN that Turkish authorities have audio and visual evidence that showed Khashoggi was killed this week inside the Saudi Consulate.

The evidence, which was described to the source by a Western intelligence agency, showed there was an assault and a struggle inside the consulate. There is also evidence of the moment that Khashoggi was killed, the source said.

The foreign intelligence service found the nature of the evidence, which was provided in a briefing from Turkish officials, to be "shocking and disgusting," the source told CNN.

Speaking to reporters Saturday in the Oval Office, Trump was asked if he had seen or heard the evidence and said "we are going to be seeing it very soon."

Trump also said the "timing is strict coincidence" between the release of Pastor Andrew Brunson from Turkish custody and the situation of Khashoggi at the Turkish consulate.

Saudi Arabia firmly denies any involvement in Khashoggi's disappearance and says he left the consulate that afternoon. But his fiancée, Hatice Cengiz, who was waiting outside the consulate, says she did not see him re-emerge. Turkey has called on Saudi officials to provide evidence he left the consulate.

Trump's comments came as a growing number of global businesses withdrew from an upcoming summit in Saudi Arabia amid concerns over Khashoggi's disappearance.

A closed-circuit TV image of Jamal Khashoggi entering the Saudi Consulate in Istanbul on October 2.

Trump: 'There's a lot at stake'

Saudi Crown Prince Mohammed bin Salman, known colloquially as MBS, spoke by phone Tuesday with Kushner and national security adviser John Bolton . US Secretary of State Mike Pompeo also spoke with the 33-year-old crown prince.

Asked by CBS journalist Lesley Stahl if bin Salman had denied Saudi involvement in Khashoggi's disappearance, Trump replied: "They deny it. They deny it every way you can imagine. In the not too distant future I think we'll know an answer."

Trump has faced mounting bipartisan pressure this week from members of Congress who are calling for him to impose stiff consequences on Saudi Arabia.

On the question of possible sanctions, Trump restated his reluctance to jeopardize a $110 billion arms deal he brokered with Saudi Arabia that was inked on his first foreign trip as President, saying he didn't want to hurt jobs. But he added, "There are other ways of punishing, to use a word that's a pretty harsh word, but it's true."

He said: "There's a lot at stake. And, maybe especially so because this man was a reporter. There's something -- you'll be surprised to hear me say that, there's something really terrible and disgusting about that if that was the case so we're going to have to see. We're going to get to the bottom of it and there will be severe punishment."

The "60 Minutes" interview is expected to air Sunday.

The US President said Friday he had not yet spoken with King Salman of Saudi Arabia -- the father of bin Salman -- in the wake of Khashoggi's reported killing, but that he planned to "pretty soon."

Turkish authorities believe 15 Saudi men who arrived in Istanbul on October 2 were connected to Khashoggi's disappearance and possible killing. At least some of them appear to have high-level connections in the Saudi government.

On Thursday, a US official familiar with the intelligence told CNN that the United States had intercepts of Saudi officials discussing a plan to lure Khashoggi back to Saudi Arabia and detain him.

Washington's "working assumption" is that Khashoggi was killed inside the consulate in Istanbul, according to another US official familiar with the latest intelligence. "We are pretty clear-eyed it is likely to have happened and it didn't end well," the official said. The source cautioned that was the latest assessment and no conclusions had been made.

Saudi government denies ordering killing

The Saudi interior minister, Prince Abdulaziz bin Saud bin Naif bin Abdulaziz, said reports that the Saudi government ordered the killing are "lies and baseless allegations against the government of the Kingdom," according to a statement the state-run Saudi Press Agency published Saturday.

Abdulaziz also said "some media" have circulated "false accusations" regarding Khashoggi's disappearance.

A delegation from Saudi Arabia has arrived in Turkey for the investigation, Turkey's state-run Anadolu Agency reported Friday.

A Saudi official said that he welcomed an announcement by Turkish President Recep Tayyip Erdogan to form a joint team of experts from both countries to investigate the disappearance," according to a Saudi Information Ministry statement.

But Saudi Arabia is not cooperating with Turkey's probe, Turkish Foreign Minister Mevlut Cavusoglu said on Saturday. "We haven't seen any collaboration yet. We want to see that."

He said Saudi authorities still need to permit Turkish police and forensic teams to enter the consulate where Khashoggi is believed to have been killed. "Where did he disappear? There, in the consulate. Therefore, for the sake of this investigation, in order to bring everything into open they must allow access to consulate."

Fiancée demands answers

Cengiz, Khashoggi's fiancée, tweeted Saturday in English and Arabic demanding information from Saudi Arabia.

"I request #SaudiArabia to officially respond to the status of my fiancée #Jkhashogji who entered the #SaudiConsulate in #Istanbul. 10 days ago and his whereabouts are still unknown to date. @JKhashoggi #whereisjamalkhashogji," the tweet in English reads.

She also tweeted that before his disappearance, she'd intended to throw a surprise party for him at a restaurant for his 60th birthday, which is Saturday.

Turkish newspaper Sabah reported Saturday that Khashoggi may have recorded his own death through his Apple Watch, and that security forces leading the investigation found the audio file inside the phone Khashoggi left with his fiancée.

CNN could not independently verify the Sabah report and was seeking comment from both Saudi and Turkish officials.

CNN intelligence and security analyst Robert Baer cast doubt on the claim , saying it was too far for a Bluetooth connection and that Khashoggi was unlikely to have anticipated transmitting a recording in advance. "I think what's happened, clearly, is the Turks have the Saudi consulate wired; they have transmitters," he said.

Businesses abandon desert summit

Saudi Arabia is facing growing isolation as firms pull out of a high-profile investment summit due to take place later this month in Riyadh.

Most of the news outlets that had agreed to sponsor the Saudi Future Investment Initiative -- known as "Davos in the desert" -- have now withdrawn.

They include Japanese media company Nikkei, CNBC, The New York Times and the Financial Times. Bloomberg said Friday it was pulling out as a media partner but added it still planned to cover news from the conference

CNN, which was a media partner for the event, confirmed Friday that it too would no longer participate in the conference. Viacom CEO Bob Bakish, Uber chief Dara Khosrowshahi and The Economist's editor-in-chief, Zanny Minton Beddoes, have also pulled out.

However, International Monetary Fund chief Christine Lagarde told reporters Saturday at the IMF's annual meeting in Indonesia she still planned to go but would be paying close attention to new information.