Ford Motor chairman Bill Ford cancelled plans to attend a Saudi investor conference, the automaker said on Sunday.

His was among the latest such high-profile announcements after the disappearance of Saudi journalist Jamal Khashoggi, a Reuters report noted.

The report said the cancellation could add pressure on other US firms like Goldman Sachs Group, Mastercard and Bank of America to reconsider their plans to attend the investor event.

Ford would not elaborate to Reuters on the reasons for the decision not to attend the Future Investment Initiative conference in Riyadh later this month, and did not comment on whether concerns about the disappearance of Khashoggi were a factor.

Khashoggi, a US resident and Washington Post columnist critical of Riyadh's policies, disappeared on 2 October after entering the Saudi consulate in Istanbul. Turkey believes he was murdered and his body removed. Saudi Arabia has denied that, the news agency added.

Reuters said the investment summit in Riyadh typically attracts executives from some of the world's largest companies and media organisations but it had rapidly become a vehicle for those firms to express their concerns over Khashoggi's disappearance.

The report said US president Donald Trump had threatened "severe punishment" if it turned out Khashoggi was killed in the consulate although he said Washington would be "punishing" itself if it halted military sales to Riyadh.

Reuters said major news organisations such as CNN, the Financial Times, the New York Times, CNBC and Bloomberg had pulled out of the conference.

The Fox Business Network, the lone western news outlet still heading to the conference, told Reuters on Sunday it was reviewing that decision.

Uber Technologies chief executive Dara Khosrowshahi was also among those who said they now were not going.

Reuters said the absence of media and technology executives was likely to case a shadow over the three day event, dubbed 'Davos in the Desert'. It had become the biggest show for investors to promote Saudi crown prince Mohammed bin Salman's reform vision.