NEW YORK - The father of a fallen Muslim-American US solider, who is of Pakistani origin, delivered a riveting, emotional speech at the Democratic National Convention in Philadelphia, during which he denounced Donald Trump, the Republican presidential nominee, for "consistently smearing the character of Muslims," and backed the candidacy of Hillary Clinton.

Capt Humayun Khan, a 27-year-old US Army captain, was killed in Iraq by suicide bombers after he waved his soldiers back, likely saving their lives, earning the Bronze Star and Purple Heart posthumously.

"We are honoured to stand here as the parents of Capt Humayun Khan, and as patriotic American Muslims with undivided loyalty to our country," Khizr Khan said in his convention address to thousands of Democratic Party delegates and watched by millions on television around the world.

“Hillary Clinton was right when she called my son the best of America,” Khan said, standing beside his wife, Ghazala. “If it was up to Donald Trump, he never would have been in America.”

Khizr then addressed the Republican candidate directly, with quiet dignity: “Donald Trump, you are asking Americans to trust you with their future. Let me ask you: have you even read the United States constitution?” Reaching slowly into his jacket, Khan then removed a small booklet and added, “I will gladly lend you my copy.”

“In this document, look for the words ‘liberty’ and ‘equal protection of law’,” he continued. “Have you ever been to Arlington cemetery? Go look at the graves of brave patriots who died defending the United States of America. You will see all faiths, genders and ethnicities.”

“You have sacrificed nothing, and no one,” he added. “We cannot solve our problems by building walls.”

Khizr continued: "Like many immigrants, we came to this country empty-handed. We believed in American democracy — that with hard work and the goodness of this country, we could share in and contribute to its blessings."

He said his son dreamed of being a military lawyer before he sacrificed his life to save other American soldiers. Then, he added, if it was up to Trump, his son would've never been in the US.

Trump's proposed indefinite barring of all Muslim immigration into the country has been championed by the candidate at various points throughout the campaign — though Trump has altered his stance on the proposal as time has passed.

"Donald Trump consistently smears the character of Muslims," he said. "He disrespects other minorities, women, judges, even his own party leadership. He vows to build walls and ban us from this country."

He asked Trump if he's ever visited Arlington National Cemetery, where the bodies of the nation's soldiers who have died in conflict lay.

"We can't solve our problems by building walls and sowing division," he continued. "We are stronger together. And we will keep getting stronger when Hillary Clinton becomes our next president." His speech was met with thunderous cheers in the hall and electrified social networks.