Saudi Arabia's king and crown prince have reportedly called the son of journalist Jamal Khashoggi to express their condolences about his death.
Saudi Arabia says the killing of journalist Jamal Khashoggi at its Istanbul consulate was a "huge and grave mistake" but it has sought to shield its powerful crown prince from the widening crisis, saying Mohammed bin Salman had not been aware.
The comments from Foreign Minister Adel al-Jubeir were some of the most direct yet from Riyadh, which has given multiple and conflicting accounts about Khashoggi's killing on October 2, first denying his death and later admitting it amid an international outcry.
The weeks of denial and lack of credible evidence in the face of allegations from Turkish officials that Khashoggi had been killed have shaken global confidence in ties with the world's top oil exporter.
US Treasury Secretary Stephen Mnuchin said Saudi Arabia's admission that the Washington Post columnist was killed in a fistfight was a "good first step but not enough," though he added it was premature to discuss sanctions against Riyadh.
Three European powers - Germany, Britain and France - pressed Riyadh to provide facts, and Chancellor Angela Merkel said Germany would not export arms to Saudi Arabia while uncertainty over Khashoggi's fate persisted.
Late on Sunday, the Saudi Press Agency said both Saudi King Salman and Prince Mohammed had called Khashoggi's son, Salah, to express condolences.
Jubeir, the Saudi foreign minister, had extended condolences to Khashoggi's family earlier on Sunday.
"This is a terrible mistake. This is a terrible tragedy. Our condolences go out to them. We feel their pain," Jubeir told the US broadcaster Fox.
"Unfortunately, a huge and grave mistake was made and I assure them that those responsible will be held accountable for this."
He said the Saudis did not know how Khashoggi, a Saudi national and US resident, had been killed or where his body was. He also said Prince Mohammed was not responsible.
"This was an operation where individuals ended up exceeding the authorities and responsibilities they had. They made the mistake when they killed Jamal Khashoggi in the consulate and they tried to cover up for it."
Khashoggi vanished after entering the consulate to obtain documents for his upcoming marriage.
After two weeks denying any involvement in the 59-year-old's disappearance, Saudi Arabia on Saturday said Khashoggi, a critic of the crown prince, died during a fight in the building. An hour later, another Saudi official attributed the death to a chokehold.
"Nothing can justify this killing and we condemn it in the strongest possible terms," Germany, Britain and France said in their joint statement.
"There remains an urgent need for clarification of exactly what happened ... beyond the hypotheses that have been raised so far in the Saudi investigation, which need to be backed by facts to be considered credible."
Reflecting international scepticism over its account, a senior Saudi government official laid out a new version that contradicts previous explanations.
The latest account includes details on how 15 Saudis sent to confront Khashoggi had threatened him with being drugged and kidnapped and killed him in a chokehold when he resisted. A member of the team dressed in Khashoggi's clothes to make it appear as if he had left the consulate.
Turkish officials suspect Khashoggi was killed inside the consulate by the Saudi agents and his body cut up. Turkish sources say authorities have an audio recording purportedly documenting Khashoggi's murder.
Turkish President Recep Tayyip Erdogan appeared to suggest on Sunday he was preparing to release information about the Turkish investigation at his weekly speech to members of his ruling AK Party in parliament.
Turkey's Anadolu agency said on Monday that Erdogan and US President Donald Trump had spoken on the telephone and agreed that "all aspects" of the case needed to be cleared up.