US Senator potential Democratic presidential candidate Bernie Sanders launched a scathing attack on the leaders of Saudi Arabia and Crown Prince Mohammed bin Salman, describing those running the country as "thug killers."

"For years we have loved Saudi Arabia as a wonderful ally, but the only problem is that the people who run that country are serial killers," Sanders said during an interview with CNN.

He added that "instead of being in a very friendly relationship with billionaire dictator Mohamed bin Salman, we can unite the Saudis and the Iranians." And that the US administration should tell the Saudis and the Iranians that they should work together, and that Washington is tired of spending trillions of dollars on endless wars.

For his part, former US envoy to Middle East peace Jason Greenblatt described Senator Sanders' statements about Saudi Arabia as dangerous and unfair.

Greenblatt said in a tweet on Twitter that he spent a lot of time with Saudi leaders for three years, and that Saudi Arabia has made great strides and there are more to come.

He pointed out that the equality of Saudi Arabia, "the important ally" of the Iranian regime, which he described as "the enemy and the murderer", is outrageous.