GENEVA (Reuters) - U.N. human rights chief Michelle Bachelet called on Saudi Arabia and Turkey on Tuesday to reveal everything they know about the disappearance and possible murder of missing journalist Jamal Khashoggi and said Riyadh should waive immunity on its diplomatic premises and officials.

United Nations High Commissioner for Human Rights Michelle Bachelet attends an ACANU briefing in Geneva, Switzerland, September 20, 2018. REUTERS/Denis Balibouse/File Photo

Overnight, Turkish crime scene investigators entered the Saudi consulate in Istanbul, the last place Khashoggi was seen before vanishing on Oct. 2, for the first time and searched the premises for over nine hours, Reuters witnesses said.

In a statement, Bachelet welcomed the investigators being given access to the consulate, despite a two-week delay, and called on authorities of both countries to ensure that “no further obstacles are placed in the way of a prompt, thorough, effective, impartial and transparent investigation.”

She urged both countries to reveal everything they know about Khashoggi’s “disappearance and possible extra-judicial killing.”

“Given there seems to be clear evidence that Mr Khashoggi entered the Consulate and has never been seen since, the onus is on the Saudi authorities to reveal what happened to him from that point onwards,” she said.

Khashoggi, a U.S. resident, Washington Post columnist and leading critic of Prince Mohammed, vanished after entering the consulate to get marriage documents.

Turkish officials say they believe he was murdered there and his body removed. CNN and the New York Times reported Saudi Arabia was preparing to acknowledge Khashoggi’s death in a botched interrogation, after denying for two weeks any role in his disappearance

It was important to immediately lift immunity for any premises and officials bestowed by the Vienna Convention on Consular Relations, she added.

“Under international law, both a forced disappearance and an extra-judicial killing are very serious crimes, and immunity should not be used to impede investigations into what happened and who is responsible,” Bachelet said.

Her spokesman Rupert Colville said: “We hope the lifting of immunity is absolute so they can investigate, in the consulate, the (consular) residence premise, the vehicles shown on TV footage.”