Trump blames George Bush for 9/11, Jeb defends brother

​Donald Trump suggested that former president George W Bush shared in the blame for the Sep 11, 2001 (9/11) terrorist attacks.

Washington: Republican presidential frontrunner ​Donald Trump waded into controversy by suggesting that former president George W. Bush shared in the blame for the Sep 11, 2001 (9/11) terrorist attacks because they happened during his presidency.

Stung by the comments, rival Jeb Bush angrily responded Friday, calling the media mogul's comment "pathetic" and asserting that his brother kept the country safe.

"How pathetic for @realdonaldtrump to criticize the president for 9/11. We were attacked & my brother kept us safe," he tweeted.

Trump ignited the controversy Friday morning when he told Bloomberg TV: "When you talk about George Bush, I mean, say what you want, the World Trade Center came down during his time."

"Hold on, you can't blame George Bush for that," interjected the Bloomberg anchor, but Trump stood by his comments.

"He was president, OK? ... Blame him, or don't blame him, but he was president. The World Trade Centre came down during his reign," Trump said.

On Friday evening, Trump took to Twitter to double down on the comment, saying he had merely been polite when Bush defended his brother during the most recent Republican debate.

"At the debate you said your brother kept us safe - I wanted to be nice & did not mention the WTC came down during his watch, 9/11," he tweeted.

"No @JebBush, you're pathetic for saying nothing happened during your brother's term when the World Trade Centre was attacked and came down," Trump tweeted about 20 minutes later.

He soon added: ".@JebBush, like it or not, our country needs more energy and spirit than you can provide! #MakeAmericaGreatAgain"

Trump has previously taken aim at Bush, calling his presidency a "disaster." And he said last week that the decision to invade Afghanistan in 2001 was a "terrible mistake."

Trump also criticised President Barack Obama for his response to the Dec 14, 2012 Sandy Hook massacre of the innocents at an elementary school in Newtown, Connecticut, that left 26 dead.

Though he did not lay the blame for the school shooting on Obama in the same way as Bush, Trump said: "If you look at Sandy Hook, those people are still begging for help. It's a disaster, and it's a disaster all over the place."

"We have tremendous potential, we have tremendous people. What we need is a leader. We don't have a leader."