|Obama's visit to Ground Zero was the first he had made since becoming president [AFP]
Barack Obama, the US president, has laid a wreath at Ground Zero in New York, where he met families of people killed in the September 11, 2001 attacks on the US.
The attacks are believed to have been ordered by Osama bin Laden, the leader of al-Qaeda, who was killed by US forces earlier this week.
The president first paid a visit to Engine 54, a fire station from where 15 firefighters died attempting to save the nearly 3,000 people who were killed after planes were flown into the World Trade Center.
Addressing the firefighters, Obama said: "What happened on Sunday because of the courage of our military and the outstanding work of our intelligence sent a message around the world but also sent a message here back home."
The president said bin Laden's death sent out the message that "when we say we will never forget, we mean what we say".
"This is a symbolic site of the extraordinary sacrifice that was made on that terrible day,' Obama said.
The president viewed a memorial plaque commemorating the firefighters who were lost and then lunched privately with a dozen firefighters.
Rudy Giuliani, the mayor of New York at the time of the attacks, joined Obama in the visit to the station.
On Friday, Obama will meet members of the team of elite commandos that carried out the covert operation inside Pakistan that killed bin Laden, a US official has said.
The president, who will visit Fort Campbell in Kentucky on Friday, "will have the opportunity to privately thank some of the special operators involved in the operation," the official, who wished to remain anonymous, said.
The White House has stressed that Obama's visit to Ground Zero was not a victory tour following bin Laden's killing, but a form of homage to the victims of the attacks that triggered Washington's "war on terror" against al-Qaeda nearly a decade ago.
Obama invited George Bush, his predecessor who was president at the time of the attacks, to join him at Ground Zero.
However, the former president decided not to attend.
"He appreciated the invite, but has chosen in his post-presidency to remain largely out of the spotlight," said Bush spokesman David Sherzer.
"This is a moment of unity for Americans and a moment to recall the unity that existed in this country in the wake of the attacks on 9/11," Jay Carney, the White House spokesman, said. "The invitation was made in that spirit."
Carney described the death of bin Laden as a "cathartic moment for the American people", adding that Obama wanted to "honour the spirit of unity in America that we all felt in the wake of that terrible attack".
"He wants to meet with them and share with them this important and significant moment, a bitter-sweet moment, I think, for many families of the victims," he said.
Obama ratings surge
The killing of bin Laden during a helicopter-borne commando raid deep inside Abbottabad is undoubtedly one of Obama's chief political triumphs since taking office in 2008, analysts said.
Polls showed an immediate surge in his ratings and even the usually squabbling Washington political establishment has rallied around the president.
The president's actions during the visit have been portrayed as part of the same attempt to retain an atmosphere of dignity in the wake of bin Laden's killing.
Obama has personally ordered that photographs of the al-Qaeda leader's dead body remain secret - despite a clamour from many people for some visual proof of his demise.
The Reuters news agency released several pictures of people killed in the operation that it said were taken by a Pakistani security official about an hour after the assault.
In an interview with 60 Minutes, the CBS news programme, to be aired on Sunday, Obama said: "It is important for us to make sure that very graphic photos of somebody who was shot in the head are not floating around as an incitement to additional violence.
"As a propaganda tool. You know, that's not who we are. We don't trot out this stuff as trophies. The fact of the matter is this was somebody who was deserving of the justice that he received.
"And I think Americans and people around the world are glad that he's gone. But we don't need to spike the football."