Republican presidential aspirant Donald Trump continues to create controversy, this time questioning the war heroism of his partymate, Arizona Senator John McCain.

During the Family Leadership Summit in Ames, Iowa, on Saturday, Trump belittled McCain's role during the Vietnam War, saying the war veteran was "captured."

"He was a war hero because he was captured. I like people who weren't captured," the controversial business tycoon said.

Trump made this comment after Republican pollster Frank Luntz, who served as moderator during the conference, described McCain as "a war hero."

McCain was a prisoner of war in Vietnam for more than five years. He was captured after his plane was shot down at the height of the war.

This was not the first time Trump criticised McCain. Earlier, the Republican presidential hopeful said the Arizona senator failed to improve the conditions of his fellow war veterans.

"John McCain has failed miserably to fix the situation and to make it possible for veterans to successfully manage their lives," Trump said on his official Twitter account.

Trump's attack on McCain's war heroism drew immediate flak from his fellow Republican presidential aspirants and also from Democratic frontrunner Hillary Clinton.

During a speech at a Democratic dinner in Little Rock, Arkansas, on Sunday, Clinton called Trump's assertion "shameful" and described McCain as a "genuine war hero."

"Donald Trump, finally a candidate whose hair gets more attention that mine," Clinton quipped.

"But, there's nothing funny about the hate he is spewing at immigrants and their families, and now the insults he's directed at a genuine war hero, Senator John McCain," she added. "It's shameful, and so is the fact that it took so long for most of his fellow Republican candidates to start standing up to him."

Former Florida Gov. Jeb Bush was among the senior Republicans who castigated Trump for his latest comment. In a tweet, the Republican presidential frontrunner said: "Enough with the slanderous attacks. @SenJohnMcCain and all our veterans –particularly POWs have earned our respect and admiration."

Here are the other tweets from members of the Republican Party:

Wisconsin Gov. Scott Walker: "@SenJohnMcCain is an American hero, period. I'll denounce any attack against his service and anyone else who wears the uniform."

Florida Sen. Marco Rubio: "America's POWs deserve much better than to have their service questioned by the offensive rantings of Donald Trump."

Former Pennsylvania Sen. Rick Santorum: "@SenJohnMcCain is an American hero, period."

Louisiana Gov. Bobby Jindal: "John McCain is an American hero. I have nothing but respect for his service to our country. After Donald Trump spends six years in a POW camp, he can weigh in on John McCain's service."

Former Arkansas Gov. Mike Huckabee: "@SenJohnMcCain is an American hero. Every breath I breathe and every step I take is free because of brave Americans like John McCain."

New Jersey Gov. Chris Christie: "I know @SenJohnMcCain. Senator John McCain is an American hero. Period. Stop."

Kentucky Sen. Rand Paul: "I don't always see eye to eye with @SenJohnMcCain. But I honor his service and the sacrifices he made for our country."

South Carolina Sen. Lindsey Graham: "At the heart of @realDonaldTrump statement is a lack of respect for those who have served—a disqualifying characteristic to be president."

Former Massachusetts Gov. Mitt Romney: "The difference between @SenJohnMcCain and @realDonaldTrump: Trump shot himself down. McCain and American veterans are true heroes."

Republican National Committee Chief Strategist and Communications Director Sean Spicer: "There is no place in our party or our country for comments that disparage those who have served honourably."

Despite being rebuked by his fellow Republicans, Trump said he will not apologise to McCain for the comments he made.

"No. Not at all," the controversial business tycoon told ABC News when asked if he owed the senator an apology.