US Republican frontrunner Donald Trump has clashed with rival Jeb Bush over his brother George's invasion on Iraq following the 9/11 attacks, Press TV reported.
"Obviously the war in Iraq is a big fat mistake," Trump said during a CBS Republican primary debate in Greenville, South Carolina on Saturday.
"George Bush made a mistake," Trump said. "We all make mistakes. But that one was a beauty ... They lied! They said there were weapons of mass destruction. And there were none."
He also slated the former president for the attacks on the World Trade Center in 2001, saying many of his friends died in the attacks that occurred "during the reign of George Bush."
Jeb Bush rejected Trump's remarks and said he was "sick and tired" of him attacking his family. "This is a man who insults his way to the nomination."
"My dad is the greatest man alive in my mind. While Donald Trump was building a reality TV show, my brother was building a security apparatus to keep us safe. And I'm proud of what he did."
Bush said that Trump criticized even his mother Barbara Bush, the wife of former president George H. W. Bush, adding "My mother is the strongest woman I know."
During the Saturday debate, Trump also attacked Sen. Ted Cruz, calling him the "single biggest liar" on the stage.
"Why do you lie?" Trump asked Cruz, when he accused the business mogul of skirting around his liberal past on Planned Parenthood and abortion.
"You are the biggest liar," Trump said when Cruz mentioned that the New York billionaire would appoint liberals to the Supreme Court.
The exchange about the Supreme Court came following the death of US Supreme Court Justice Antonin Scalia on Friday that loomed large during the debate with over 9,000 mentions during the first half.
According to two new polls by Georgia-based Opinion Savvy and South Carolina House Republican Caucus, Trump is ahead of his rivals in South Carolina.
The polls released on Friday showed that Trump's support had gone up since his triumph in New Hampshire where he won 35.3 percent of the vote.