Washington, May 1 (IANS/EFE): Republican hopeful for the US presidency Donald Trump said those who protested against him in the California Republican Party convention were thugs and criminals, the media reported.

"The 'protesters' in California were thugs and criminals. Many are professionals. They should be dealt with strongly by law enforcement!" Trump wrote on his Twitter account on Saturday.

The New York magnate, leader by a wide margin in the Republican primaries for the presidential candidacy, made that comment about demonstrations in the town of Burlingame near San Francisco, during which hundreds of protesters clashed with police.

The presence of demonstrators forced Trump, who was taking part in the California GOP convention that ends on Sunday, to enter the hotel by the back door.

"That is not the easiest entrance I've ever made. We went under a fence and through a fence. Oh boy, it felt like I was crossing the border, actually. I was crossing the border, but I got here," said Trump, who has made his controversial remarks about building a wall along the Mexican border one of the planks of his campaign platform.

The disturbances came after at least 20 people were arrested following protests at another electoral event of the likely GOP candidate at Costa Mesa in Southern California.

"I'm protesting because I want equal rights for everybody," 19-year-old Daniel Lujan told the Los Angeles Times.

Lujan was one of the hundreds of people - mostly Latinos, according to the newspaper - filling the streets to protest against Trump.