US president Barack Obama leads commemorations on 14th anniversary of 9/11 attacks

Barack Obama and first lady Michelle Obama today led a moment's silence at the White House as hundreds of victims' relatives gathered at Ground Zero to mark the 14th anniversary of 9/11.

The US president and his wife stepped out of their official residence at 8.46am, when the first plane hit the north tower, and placed hands over their hearts as a bugler played the Last Post.

At the same time relatives of those killed gathered in New York for commemorations at the scene of the terrorist attacks on the World Trade Center.

"We come every year. The crowds get smaller, but we want to be here. As long as I'm breathing, I'll be here," said Tom Acquaviva, 81, who lost his son Paul when the north tower was hit.