The Turkish president has vowed to reveal the “naked truth” about the killing of journalist Jamal Khashoggi at the Saudi consulate in Istanbul.
Recep Tayyip Erdogan, who has stopped short of blaming the Saudis, is due to address members of his ruling AK party.
Turkish officials say they have evidence to show Khashoggi was murdered in the consulate on 2 October.
After weeks of conflicting accounts, the Saudis now say he was killed in a rogue operation.
Tuesday’s address by President Erdogan coincides with the start of an investment conference in Saudi Arabia that has been overshadowed by the Khashoggi case, with dozens of government and business leaders pulling out.
Many world leaders have condemned the murder of the Washington Post contributor and demanded a full investigation.
In his latest comments on the case, US President Donald Trump appeared to support Saudi Arabia’s version of events, telling USA Today he still believed the killing was “a plot gone awry”.
Despite the growing concern, US Treasury Secretary Steven Mnuchin held talks with Saudi Arabia’s crown prince in Riyadh on Monday.
BBC