© Provided by TheNewArab Former US presidential hopeful Bernie Sanders has slammed Saudi Arabia over allegations that it killed critical journalist Jamal Khashoggi inside its Istanbul consulate.

Former US presidential hopeful Bernie Sanders has slammed Saudi Arabia over allegations that it killed critical journalist Jamal Khashoggi inside its Istanbul consulate.

The veteran senator made the comments during a speech on Tuesday, condemning US President Donald Trump for inspiring "authoritarian leaders" such as Saudi Crown Prince Mohammed bin Salman.

"If the Saudi regime murdered a journalist critic in their own consulate, there must be accountability," Sanders said.

"There must be an unequivocal condemnation by the US. But it seems clear that bin Salman feels emboldened by the Trump administration's unquestioning support,"

Sanders said bin Salman was inspired to start a recent diplomatic spat with Canada because he knew Trump would remain silent on the issue.

Khashoggi, who has been critical of Prince Mohammed, went missing a week ago after visiting the kingdom's consulate in Istanbul.

Turkish officials believe he was murdered inside the consulate. Riyadh denies the claim, saying he left the compound on his own.

Trump, a close ally of Riyadh, told reporters on Tuesday that he knew nothing about Khashoggi's fate.

"I am concerned. I don't like hearing about it. Hopefully that will sort itself out," he added.

The US State Department said in a statement on Tuesday that it called on Riyadh to support a thorough investigation of Khashoggi's disappearance.

Trump stayed silent on Saudi human rights issues as the US backs the devastating Saudi-led air campaign against rebels in Yemen, which a UN report said has killed thousands of civilians.

The US leader also failed to condemn Prince Mohammed after he detained dozens of people last year in a controversial crackdown.

Under the young prince, Saudi Arabia has increasingly shown it will not tolerate any criticism.

In August, the kingdom expelled the Canadian ambassador and froze all trade and investment after Ottawa voiced concern for jailed rights activists in the kingdom.