A Saudi citizen waits behind the security barriers to enter the Saudi Consulate in Istanbul, Turkey October 8, 2018. REUTERS/Murad Sezer

GENEVA (Reuters) - The United Nations human rights office voiced deep concern on Tuesday at the “apparent enforced disappearance” and possible murder of Saudi journalist Jamal Khashoggi a week ago and urged the two countries to investigate.

Turkish President Tayyip Erdogan on Monday asked Riyadh to prove its claim that Khashoggi had left the Saudi consulate in Istanbul, while Washington urged Saudi Arabia to support an investigation into his disappearance.

“Yes, this is of serious concern, the apparent enforced disappearance of Mr Khashoggi from the Saudi consulate in Istanbul,” U.N. human rights spokeswoman Ravina Shamdasani told a Geneva news briefing.

“If reports of his death and the extraordinary circumstances leading up to it are confirmed, this is truly shocking,” she said.

Khashoggi was previously a prominent newspaper editor in Saudi Arabia and an adviser to a former head of intelligence. His disappearance has sparked global concern, particularly after Turkish sources said over the weekend that authorities believed he had been killed inside the consulate.

“We call for cooperation between Turkey and Saudi Arabia to conduct a prompt and impartial investigation into the circumstances of Mr Khashoggi’s disappearance and to make the findings public,” Shamdasani said. The two countries have such an obligation under both criminal law and international human rights law, she said.

(Fixes quote in fourth paragraph to say “If reports ... are confirmed”, not “... are true”; no other changes.)