The crown prince is likely to appear on a panel alongside Lebanon's prime minister-designate Saad Hariri, whose resignation in a televised address from the Saudi capital in mysterious circumstances last year sparked rumours he was being held against his will.

The conference, nicknamed "Davos in the desert", has been overshadowed by the outcry over the murder of Khashoggi inside the kingdom's consulate in Istanbul on October 2, with a array of big names pulling out over the case.

The reform credentials of Prince Mohammed, the king's powerful son, have been tarnished by the scandal despite repeated denials he had any involvement in the killing of the Washington Post contributor.

Saudi organisers of the conference have sought to portray it as business as usual, announcing 12 "mega deals" worth more than $50 billion in oil, gas, infrastructure and other sectors on the opening day of the forum.

Energy Minister Khalid al-Falih acknowledged, however, that the kingdom was in crisis following the "abhorrent" murder of Khashoggi.

Saudi Arabia initially claimed Khashoggi left freely after visiting the consulate but, as international pressure mounted, the kingdom said he died inside the mission when an argument degenerated into a fistfight. It later acknowledged that he had in fact been murdered, as Turkish officials said all along.

The move came as Turkish President Recep Tayyip Erdogan said in a keenly anticipated speech on Tuesday that Khashoggi's killing inside the consulate had been meticulously planned.afp