A Saudi prince has described US businessman Donald Trump, a candidate for the Republican presidential nomination, as a "disgrace to America".
Prince Alwaleed bin Talal said on Twitter that Mr Trump should give up his presidential ambitions because he would never win.
It follows Mr Trump's call for Muslims to be barred from entering the US for security reasons.
Mr Trump tweeted back, calling the prince "dopey".
Who is Prince Alwaleed?
- Born in 1955
- Nephew of King Salman bin Abdulaziz al-Saud
- Completed a business degree in California in 1979
- Named world's richest Arab in Forbes' 2015 list
- Worth an estimated $32bn (£20bn)
- Has vowed to donate fortune to charity
- Has stakes in Disney, 21st Century Fox, News Corp, Apple, GM, Twitter, and a string of hotel chains and luxury hotels, including the Plaza in New York and the George V in Paris
- Owner of 95% of Kingdom Holdings, a publicly-traded company on the Saudi stock exchange
- Considered Westernised and progressive on most issues. Champions women's rights - most of his staff are women
"You are a disgrace not only to the GOP [Republican Party] but to all America," Prince Alwaleed tweeted.
"Withdraw from the US presidential race as you will never win."
Mr Trump responded by accusing the prince of wanting to use what he called "daddy's money" to control US politicians.
That would not happen, Mr Trump said, when he got elected.
Mr Trump, the frontrunner for the 2016 Republican presidential nomination, has been widely criticised for his call for a ban on Muslims entering the US.
On Thursday, Damac Properties - a Dubai firm building a golf complex with Mr Trump - removed his name and image from the property.
His comments came following the California shootings, carried out by two Muslims who the FBI said were radicalised.