A US judge dismissed Tuesday a lawsuit against Saudi Arabia's Crown Prince Mohammed bin Salman for his alleged role in the 2018 murder of dissident journalist Jamal Khashoggi.

Washington federal judge John Bates accepted 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.

Bates said the civil suit filed by Khashoggi's widow Hatice Cengiz and his activist group DAWN made a "strong" and "meritorious" argument that Prince Mohammed was behind the murder.

But he ruled that he had no power to reject the US government's official stance, submitted in a formal statement to the court on November 17, that the prince had immunity as a foreign leader.

Even if the prince was named prime minister just weeks ago, the US government's executive branch "remains responsible for foreign affairs, including with Saudi Arabia, and a contrary decision on bin Salman’s immunity by this Court would unduly interfere with those responsibilities," Bates said.

He said the "credible" allegations of the murder, the timing of prince's being named prime minister, and timing of the US government's submission, left him with "uneasiness."

But Bates said he had no other choice in the case.

-- US intelligence blamed prince --

Prince Mohammed has been the kingdom's de facto ruler for several years under his father King Salman.

One of the prince's most vocal critics, Khashoggi was a journalist and activist based in the United States when he traveled to Turkey with his fiancee to obtain documents for their marriage from the Saudi consulate in Istanbul.

After he entered the consulate Khashoggi was seized and murdered by a team of agents of the Saudi regime, his body dismembered and disposed of.

Activists seeking to hold the crown prince accountable for the Khashoggi murder voiced dismay.

"Today is a dark day for victims of transnational repression," said Khalid Aljabri, a US-based doctor and son of a former Saudi intelligence official.

US President Joe Biden "has put dissidents at greater risk while confirming to dictators that his human rights policy is nothing but hot air."

A Saudi court in 2020 jailed eight people for between seven and 20 years over the killing.

Last year, Biden declassified an intelligence report that found Prince Mohammed had approved the operation against Khashoggi, an assertion Saudi authorities deny.

The murder deeply strained ties between Washington and Riyadh.

But driven by the needs of Middle East politics, particularly the threat from Iran, and Saudi Arabia's power over oil markets, Biden traveled to the country in July in a move seen as partially aiming to put the murder case behind.

Nevertheless, while there Biden made mention of it in his talks with the crown prince, calling the murder "outrageous."