The photos provoked a strong reaction on social media, with many commentators speculating on how tough it must have been for Khashoggi's son to shake hands with the man accused of organising his father's murder. Later on Tuesday, the Crown Prince attended the investment forum alongside King Abdullah II of Jordan. Crown Prince Mohammed sat front-row in the audience of an afternoon session and then looked at some promotional booths outside the main hall as an excited crowd of mostly young Saudi men filmed the encounter on their phones.

Khashoggi's death loomed large over the start of the event, known as the Future Investment Initiative, which came as Turkish President Recep Tayyip Erdogan said on Tuesday that Saudi officials murdered Khashoggi in their Istanbul consulate after plotting his death for days. The Turkish leader demanded the kingdom reveal the identities of all involved in the killing, regardless of rank. Loading Replay Replay video Play video Play video Saudi Arabia, which for weeks maintained Khashoggi had left the consulate, on Saturday acknowledged he was killed there in a "fistfight". Turkish media and officials say a 15-member Saudi team was flown in to kill Khashoggi. They say the team cut off his fingers before killing and dismembering the 59-year-old Washington Post columnist, who had written critically about the Crown Prince. Crown Prince Mohammed has come under mounting pressure, with critics suspecting he ordered the high-profile operation or at least knew about it. Saudi authorities say they have arrested suspects and dismissed senior officials, but the crown prince has thus far escaped blame.

At the opening of the conference, Saudi Energy Minister Khalid al-Falih described the journalist's killing as "abhorrent". Some of the forum's keynote speakers and numerous Western executives and officials had cancelled plans to attend over Khashoggi's October 2 slaying. Saudi Crown Prince, Mohammed bin Salman, smiles as he attends the Future Investment Initiative conference. Credit:AP "As we all know, these are difficult days for us in the kingdom of Saudi Arabia," al-Falih said in a speech to attendees seated in the forum's ornate hall. "Nobody in the kingdom can justify it or explain it. From the leadership on down, we're very upset at what has happened," he added, referring to Khashoggi's slaying.

The forum is the brainchild of Crown Prince Mohammed and is aimed at drawing more foreign investment into the kingdom to help create desperately needed jobs for millions of young Saudis entering the workforce in the coming years. Despite the absence of key executives and speakers from the United States and other Western partners, some $US50 billion ($70 billion) in deals were signed on Tuesday at the forum, with Russian and Asian businesses and officials eager to do business with the kingdom. "Those partners who are here with us today to continue that journey with us are certainly going to look back and find out... how committed the kingdom is to its partners that stay the course," al-Falih said, just moments before several deals were inked on stage. Loading Replay Replay video Play video Play video The forum last year grabbed headlines when Crown Prince Mohammed wowed the crowd of global business titans with pledges to lead the ultraconservative kingdom toward "moderate Islam". He also announced plans to build a $US500 billion futuristic city in the desert.

At the time, Crown Prince Mohammed spoke on stage alongside Stephen Schwarzman of US private equity firm Blackstone. Loading Schwarzman is among those who've backed out of attending this year. Others include US Treasury Secretary Steven Mnuchin, who met with Crown Prince Mohammed separately before the forum, according to Saudi state television. Among its many investments domestically and abroad, Saudi Arabia's sovereign wealth fund, which the Crown Prince oversees, has invested $US20 billion in a US-focused infrastructure fund with Blackstone. The Public Investment Fund has also invested $US3.5 billion in ride-sharing firm Uber, whose chief executive Dara Khosrowshahi also backed out of attending this year's forum.

Lubna Olayan, a Saudi businesswoman moderating the forum's first session on Tuesday, opened with remarks about Khashoggi. Loading "As we gather here in Riyadh this morning, it is natural that our thoughts tend to focus on recent events surrounding the death of Jamal Khashoggi - a writer, a journalist and a Saudi journalist known to many of us," she said. "May he rest in peace." She added that such "terrible acts... are alien to our culture and DNA". Some in the crowd applauded her remarks. Directors of the Saudi, Russian and United Arab Emirates' sovereign wealth funds took part in the opening panel. Pakistan's Prime Minister Imran Khan headlined another session, with Jordan's King Abdullah II expected to speak at the forum on Wednesday.