Washington federal judge John Bates accepts a US government's stance that Prince Mohammed, who was designated prime minister of Saudi Arabia in September, enjoys immunity in US courts as a foreign head of state.

The White House reaction comes as Amnesty International blasts the Biden administration over granting immunity to the prince, calling the act 'a deep betrayal'.

They say the crown prince's appointment as prime minister last week ensures him immunity from prosecution.

On a trip to reset relations with a country he had called a pariah after Khashoggi's killing in 2018, Biden said the crown prince denied involvement in the murder and said he had held those responsible to account.

The two countries will sign several agreements during his trip as Turkey looks to non-Western partners for financial support as soaring inflation bites.

Analysts and officials say Saudi funding could help boost Turkey's ailing economy.

The city council says it will be a memorial in his honour 'that cannot be covered up or repressed'.

The scandal allegedly prompted the US to suspend several security programmes, including wide-reaching efforts to modernise Riyadh's intelligence agencies.

The complaint includes allegations of arbitrary detention of more than 30 journalists and the murder of Washington Post columnist Jamal Khashoggi.

The report says that given Prince Mohammed's influence, it is 'highly unlikely' that the 2018 murder could have taken place without his green light.

The judge has also instructed the CIA and Office of the Director of National Intelligence to explain why they are withholding the tape and a CIA report on the gruesome killing.

MBS could face legal trouble as the former spy boss accuses him of trying to murder him 'Kashoggi-style'.