U.S. Republican presidential front-runner Donald Trump's political rhetoric is "racist," and evocative of Adolf Hitler, former Mexican President Felipe Calderon told reporters at an event in Mexico City on Saturday.

"This logic of praising the white supremacy is not just anti-immigration," Calderon said. "He is acting and speaking out against immigrants that have a different skin color than he does, it is frankly racist and [he is] exploiting feelings like Hitler did in his time," Calderon said.

Trump has been widely criticised for his hard line on immigration. He has pledged to build a wall to slow down the number of Mexicans entering the United States, and in July last year claimed that Mexican immigrants were responsible for a significant number of rapes in America.

He has also called for a ban on all Muslim immigrants; a line that was later used by Somali terrorist group al-Shabaab to suggest that America discriminated against its Islamic population.

Felipe Calderon was president of Mexico from 2006-12.

Former Mexican President Vicente Fox, Calderon's predecessor, also compared Trump to Hitler in an interview with Anderson Cooper on CNN.

"He reminds me of Hitler," Fox told Cooper on Friday.