New York: President Barack Obama during an emotional visit to the 9/11 Ground Zero said that al-Qaeda chief Osama bin Laden’s killing by US Special Forces show America’s unfailing commitment to bring terrorists to justice.

Days after bin Laden was killed in Abbottabad near the Pakistani capital Islamabad, Obama, who made his first visit to Ground Zero on Thursday night since becoming President, told a crew of fire fighters that lost 15 members during 9/11 attacks that the al-Qaeda chief's death was a string message both to the world and to the Americans.

"When we say we will never forget, we mean what we say," he said at a stop before laying a wreath at the site of the terror attack.

"What happened on Sunday... sent a message around the world, but also sent a message here back home... that our commitment to making sure that justice is done is something that transcended politics, transcended party," he said.

Obama said it did not matter which administration was in, America was always going to make sure "the perpetrators of that horrible act -- that they received justice".

After laying wreath at the site, Obama met relatives of around 3,000 people who had died in the attacks on September 11, 2001.

Obama said while the lost ones would never return, he hoped the efforts of the US forces to hunt down the perpetrator in Pakistan would bring some sense of closure to the victims.

"So it's some comfort, I hope, to all of you to know that when those guys took those extraordinary risks going into Pakistan, that they were doing it in part because of the sacrifices that were made in the States. They were doing it in the name of your brothers that were lost," he said.

He also visited a Manhattan police station to speak to some of the first responders and told them: "I am here basically to shake your hand and say how proud I am of all of you".

As Obama visited the Ground Zero, crowds with flags and cameras lined up the street.