US Senator John McCain (R-Ariz.) says business mogul Donald Trump owes an apology to military families for remarks about him not being a war hero.

Trump, a Republican presidential candidate for 2016, drew sharp criticism after he suggested McCain, a former US Navy fighter pilot imprisoned for more than five years during the Vietnam War, was not a war hero.

“I think he may owe an apology to the families of those who have sacrificed in conflict and those who have undergone the prison experience in serving their country,” McCain said on MSNBC's "Morning Joe" Monday.

"There are so many men, and some women, who served and sacrificed and happened to be held prisoner and somehow to denigrate that, in any way, their service I think is offensive," he added.

Trump backtracked from the comments he made to a Republican forum over the weekend. However, he has refused to apologize even as his rivals for the GOP nomination have called on him to do so.

“He’s not a war hero,” Trump said at the time. “He’s a war hero because he was captured? I like people who weren’t captured.”

He insisted Saturday that he was criticizing McCain for “not doing enough for our veterans.”

Former Florida Governor Jeb Bush called Trump’s comment "slanderous," and Wisconsin Governor Scott Walker said he "needs to apologize."

Former Texas Governor Rick Perry and South Carolina Senator Lindsey Graham have suggested Trump should drop out of the race.

“If there was ever any doubt that Donald Trump should not be our commander in chief, this stupid statement should end all doubt,” Sen. Graham said.