US 'saddened' by confirmed Khashoggi death: White House

In the first US response to Saudi Arabia's admission, White House spokeswoman Sarah Sanders said merely that Washington "acknowledges the announcement".

"We will continue to closely follow the international investigations into this tragic incident and advocate for justice that is timely, transparent and in accordance with all due process," she said.

"We are saddened to hear confirmation of Mr Khashoggi's death, and we offer our deepest condolences to his family, fiancee and friends."

However, the statement made no mention of US action against its major Saudi ally, despite US President Donald Trump warning earlier in the week of "very severe" consequences should Saudi Arabia be proven responsible.

Speaking to journalists in Washington Trump said the potential US response to Saudi Arabia, which is accused of murdering the Washington Post columnist and critic of the Saudi regime would "have to be very severe. It's bad, bad stuff".

This marked a hardening of tone from the Trump administration, which has been reluctant to blame ally Saudi Arabia, despite mounting evidence that Saudi agents killed and dismembered Khashoggi inside the Saudi consulate in Istanbul more than two weeks ago.

A former regime insider, Khashoggi had become a critic of the powerful Crown Prince Mohammed bin Salman, the point man in ever-tightening military and commercial relations between the Muslim petro-state and the Trump administration.

Just hours earlier Secretary of State Mike Pompeo said the US would decide on an action only when Riyadh completes an investigation.

Early on Saturday, Saudi authorities finally admitted to the death of Khashoggi in its Istanbul consulate after two weeks of denials amid lurid and grisly allegations detailing Khashoggi's death leaked by Turkish police and others.

Riyadh authorities said 18 Saudi nationals were being investigated for their involvement in the murder, noting a royal order dismissing Ahmad al-Assiri, the deputy intelligence chief and former spokesman for the Saudi-led coalition fighting in Yemen, alongside Saud al-Qahtani, a senior aide to Crown Prince Mohammed bin Salman.

The acknowledgment of Khashoggi's death came after staff members from Saudi Arabia's consulate in Istanbul testified on Friday at the chief prosecutor's office as part of a probe into his disappearance, Anadolu reported.

Fifteen staff, all Turkish nationals, were giving statements, according to NTV television. The development follows a thorough search of the consulate and the residence of the consul by Turkish authorities.

Washington Post columnist Khashoggi disappeared on 2 October when he entered the Saudi consulate in Istanbul to complete some routine paperwork. Khashoggi had been living in self-imposed exile in the United States after fearing for his own safety in Saudi Arabia.