Peruvian Nobel prize-winning author Mario Vargas Llosa said on Tuesday that Donald Trump was a "clown" and a "racist" who would doom the Republican party to defeat if it chose him as its candidate for November's U.S. presidential election.

"He is a danger to the United States," said Vargas Llosa, who himself ran as a center-right candidate for the Peruvian presidency in 1990.

"It is a country that is too important for the rest of the world to have in the White House a clown, a demagogue and a racist like Mr Trump," he told a news conference in Madrid to launch his new novel, "Cinco esquinas" ("Five Corners").

Trump, the frontrunner in the Republican primaries, has said he wants to build a wall along the U.S. border with Mexico and deport 11 million illegal immigrants. He also suggested, at his campaign launch last June, that Mexican immigrants were rapists and drug dealers.

Vargas Llosa said Trump's "seemingly unstoppable" campaign would guarantee another term for the Democratic party.

"Hillary Clinton surely will win a massive victory if the Republican candidate is Donald Trump," he said.

Vargas Llosa, 79, won the Nobel Literature Prize in 2010 and now lives mainly in Madrid. He is known for books such as "The Time of the Hero" that explore Latin America's structures of political power.

(This version of the story corrects translation in headline and first and third paragraphs to "racist" from "fascist")

(Reporting by Angus Berwick; Editing by Sonya Dowsett and Kevin Liffey)