Iranian Prez Hassan Rouhani says Saudi wouldn't have murdered Khashoggi under US backing

Saudi journalist Jamal Khashoggi's "heinous murder" would have been unthinkable "without US backing," Iranian President Hassan Rouhani said on Wednesday.

"I don't think that any country would dare to do such a thing without US backing," Rouhani said in remarks to cabinet broadcast on state television.

Rouhani said that before Khashoggi's murder "it would have been unthinkable that in this day and age we would witness such an organised felony.

"It is extremely significant that an institution planned such a heinous murder.

"The tribal group that is ruling that nation (Saudi Arabia) has a security margin. That security margin is that it relies on US backing. It is this superpower that is backing them."

Khashoggi, a government critic who was living in self-imposed exile in the United States, was murdered inside the Saudi consulate in Istanbul on October 2 as he organised the paperwork for his marriage to his Turkish fiancee.

The case has triggered an international outcry against Saudi Arabia. US President Donald Trump on Tuesday ridiculed Riyadh's response as "one of the worst cover-ups" in history.

The Sunni kingdom and Shiite Iran are fierce rivals which have long been engaged in a struggle for influence in the Middle East.