A Saudi prince has urged Americans not to vote for Donald Trump in the upcoming general election.

Turki al-Faisal, who served as Saudia Arabia's ambassador to the US from 2005 to 2007, spoke against the presumptive Republican nominee during a foreign policy dinner in Washington, DC on Thursday.

He blasted Trump's proposal to ban Muslims from entering the US, which the billionaire first formulated in December last year before renewing his vow on Wednesday.

'For the life of me, I cannot believe that a country like the United States can afford to have someone as president who simply says, "These people are not going to be allowed to come to the United States,''' Turki said according to the Huffington Post.

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Turki al-Faisal (pictured in September last year), a former ambassador to the US, spoke against the presumptive Republican nominee during a foreign policy dinner in Washington, DC on Thursday

'It's up to you, it's not up to me,' Turki added. 'I just hope you, as American citizens, will make the right choice in November.'

Turki, who went to Georgetown University in Washington, DC, isn't currently part of Saudia Arabia's government but serves as the chairman of the King Faisal Center for Research and Islamic Studies, a cultural organization that conducts research in politics, sociology and heritage.

He spoke Thursday at a dinner hosted by the Washington Institute For Near East Policy at the Mandarin Oriental hotel.

Turki said he had enjoyed the 'spectacle' of American elections during his time as a student in the US in the 1960s, the Huffington Post write, and found it 'sometimes uplifting, other times the opposite.'

Trump (pictured at a rally in Charleston, West Virginia, on Thursday) first proposed to ban Muslims from coming into the US in December last year to prevent terrorist attacks and stuck by his plan on Wednesday

Trump first proposed to ban Muslims from coming into the US in December last year to prevent terrorist attacks.

He stuck by his plan on Wednesday, saying on MSNBC's Morning Joe he didn't care if it hurt him in the general election.

'I'm doing the right thing when I do this. And whether it's Muslim or whether it's something else, I mean, I have to do the right thing, and that's the way I've been guided,' he said.

'And I've been guided by common sense, by what's right. And you see what's happening. We have to be careful. I mean, we're allowing thousands of people to come into our country, thousands and thousands of people being placed all over the country that frankly nobody knows who they are.