Donald Trump's proposal of a blanket ban on all Muslims entering the United States received harsh criticism on Wednesday, not just from the presidential hopeful's political rivals, but also from world leaders and GOP heavyweights.

The prime ministers of France and the United Kingdom were among the first to dismiss the suggested "total and complete shutdown" of all federal processes allowing followers of Islam into the country, The New York Times reported.

"Mr. Trump, like others, fuels hatred. Our only enemy is radical Islamism," Manuel Valls, the French premier, insisted on social media.

David Cameron, his British counterpart, called the idea "divisive, unhelpful and quite simply wrong."

The highest ranking Republican officeholder in the United States, House Speaker Paul Ryan, meanwhile, slammed the proposal as un-American, The Hill noted.

"This is not who we are as a party or a country," Ryan told GOP congressmen during a closed-door meeting. The speaker's remarks were met with applause, an unidentified source told the Washington publication.

Trump, for his part, defended his initiative as a necessary step to protect Americans from violent jihadism, according to Reuters.

"What I'm doing is no different than (President Franklin D. Roosevelt)," Trump said on ABC's "Good Morning America," pointing to the World War II-era internment of more than 110,000 people in U.S. government camps after Japanese forces bombed Pearl Harbor on Dec. 7, 1941.

"We have no choice but to do this," the real estate tycoon added. "We have people that want to blow up our buildings, our cities. We have to figure out what's going on."

But Rachid Tlemcani, a professor of political science at the University of Algiers, told The New York Times that Trump's comments could actually help draw young people toward Islamic terror groups such as ISIS and al Qaeda.

"A lot of people in the Middle East think of the United States as the last place we can go if things turn really bad, as it is the place of freedom and liberty," Tlemcani said. "I think that sort of comment could even invite some act of violence against America. I think he is not responsible."