Pentagon Chief Jim Mattis warned Arab leaders on Saturday that the murder of Saudi journalist Jamal Khashoggi inside the kingdom's consulate in Istanbul “must concern us all”.

The United States (US) “does not tolerate this kind of ruthless action to silence Mr Khashoggi, a journalist, through violence,” Mattis told a meeting in the Bahraini capital Manama.

“Failure of any nation to adhere to international norms and the rule of law undermines regional stability at a time when it is needed most.”

A critic of Saudi Arabia's powerful Crown Prince Mohammed bin Salman, Khashoggi was murdered after entering the Saudi consulate in Istanbul on October 2.

On Thursday, Central Intelligence Agency (CIA) Director Gina Haspel briefed US President Donald Trump on the latest developments in the investigation after a fact-finding mission to Turkey.

Pro-government Turkish media said that intelligence officers showed Haspel video images and audio tapes of Khashoggi's killing gathered from the consulate.

His murder has generated international outrage and undermined relations with Riyadh, which Washington is hoping can help counter Tehran's influence in the Middle East.

Prince Mohammed, the kingdom's de facto ruler, has denounced the “repulsive” murder, denying any involvement. The kingdom's leadership has pushed responsibility down the chain of command.

Trump has called the case “one of the worst cover-ups in history”.

Washington moved late Tuesday to revoke the visas of several Saudis and Britain followed suit on Wednesday.

Mattis said more measures would follow.

“We will maintain our 'twin imperatives', as stated by Secretary of State (Mike) Pompeo, of protecting America and holding accountable those responsible for this murder,” he told the forum. “Our secretary of state has already revoked visas and will be taking additional measures."

Khashoggi killers 'will be prosecuted in Saudi Arabia': Saudi FM

Saudi Arabia will prosecute the suspects in the killing of Khashoggi, Riyadh's foreign minister said Saturday in response to a call by Turkey for their extradition.

"On the issue of extradition, the individuals are Saudi nationals. They're detained in Saudi Arabia, and the investigation is in Saudi Arabia, and they will be prosecuted in Saudi Arabia," Foreign Minister Adel al-Jubeir said at the regional defence forum in the Bahraini capital.

Jubeir's comments come the day after Turkish President Recep Tayyip Erdogan called for the extradition of 18 Saudi nationals authorities say were involved in the murder of Khashoggi, a Saudi government critic killed in his country's consulate in Istanbul this month.

After denying knowledge of Khashoggi's whereabouts for nearly three weeks, Riyadh admitted Khashoggi's murder had been "premeditated" but denied the involvement of the kingdom's powerful Crown Prince Mohammed bin Salman.

"We will overcome it," Jubeir told the defence forum.

"The issue, as I said, is being investigated. We will know the truth. We will hold those responsible accountable. And we will put in place mechanisms to ensure it doesn't happen again."

Khashoggi was least seen entering the Saudi consulate in Istanbul on Oct 2 to complete paperwork for his wedding to his Turkish fiancee, Hatice Cengiz.

She has demanded punishment of everyone involved in his murder "from the highest to the lowest levels".