New Yorkers have been taking part in a moving ceremony at the site of the fallen twin towers exactly one year after the attacks on the World Trade Center - with the names of each of the 2,801 people who died there read out.

We renew our commitment to win the war that began here

President Bush at the Pentagon

The ceremony at the site now known as Ground Zero began at 0846 local time (1246GMT/1346BST) with a minute's silence to mark the moment when the first of two hijacked passenger jets was crashed into the World Trade Center.

Other ceremonies to mark the anniversary are being held across the United States and the world, while at the United Nations, Secretary General Kofi Annan led a minute's silence.

	:	In pictures
The world remembers

President George W Bush told workers at the Pentagon that America was renewing its commitment to win the war against terrorism.

Paying tribute to the 184 people who were killed in the 11 September attack on the Pentagon, Mr Bush said: "Although they died in tragedy, they did not die in vain."

Shanksville honoured the 40 people who died there

Mr and Mrs Bush then laid a wreath in Shanksville, Pennsylvania, where the last of the four planes crashed after passengers tried to overpower the hijackers.

The couple met the families of the 40 people who died there, as hundreds of friends and relatives, clutching flowers and American flags, gathered at the field where the plane came down.

The president was joined by about 100 of his own White House staff, who believe that their lives may have been saved by the passengers who prevented the hijackers from flying the aircraft into a target in Washington.

President Bush is now at Ground Zero where he has been taking part in a wreath-laying ceremony.

Later he travels to Ellis Island where, with the Statue of Liberty behind him, he will address the nation at 2200 (0200GMT).

Moments of silence

In New York, the day began with the city's firefighters and police, who lost hundreds of their members on 11 September last year, marching to the site from each of the city's five boroughs to the mournful accompaniment of bagpipers.

	The Gettysburg Address New York state Governor George Pataki read Abraham Lincoln's famous 1863 Civil War speech, at the ceremony at Ground Zero. Click here for the full text

At Ground Zero, a string quartet played as the city's former Mayor, Rudolph Giuliani, led the reading of the names of those who died.

Gordy Aamoth, who worked in the 104th floor of the south tower, was the first name to be read out.

Relatives, emergency workers and other prominent New Yorkers took part in the reading. Around them, families - many of them holding pictures of those they lost - laid flowers.

The Governor of New York, George Pataki, gave a reading from Abraham Lincoln's Gettysburg Address. There was also a reading from the US Declaration of Independence.

Two moments of silence were observed marking the precise time when the planes crashed into the towers. A bell was rung at 1029 local time (1429GMT) - when the second tower collapsed.

I still get upset at the thought of these poor children who lost their parents - I pray for them all

Alison C, West Midlands, UK

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Nearby, at UN headquarters, a Security Council meeting of foreign ministers paid tribute to the victims of the attacks.

They called on all states to continue the fight against terrorism.

Kofi Annan told the meeting that terrorism could be defeated if the international community worked together in a broad coalition.

The ministers will later join President Bush and other heads of state at New York's Battery Park, where an eternal flame is to be lit.

Many had pictures of the relatives they lost

Security has been tightened within the US and at potential Western targets across the globe amid fears that the anniversary may be marked by further attacks.

Fighter planes are patrolling the skies above key American cities - which are also being protected by missile batteries - while some Western embassies in potential hotspots have been closed.

Osama Bin Laden's al-Qaeda terror group, widely blamed for the 11 September attacks, has lost its base in Afghanistan following the collapse of the Taleban regime - but is still perceived as a major threat.