Steve Morris: Still missing

Only four have been positively identified - the rest are recorded missing.

The Queen, senior members of the government and a delegation from the US, including former president George Bush senior, are among those gathering at Westminster Abbey in London for the hour-long service at 1200GMT.

Stephen Morris, 31, from Nantglyn, near Denbigh, is believed to have been working high up in the north tower - on the 97th floor - when it was hit in the initial attack.

Thousands missing

A banker from Wales who was called to a meeting in the WTC just minutes before the attacks is also among the missing.

Nicholas John, 42, originally from Dunvant in Swansea, had travelled from his normal base in an office block several blocks away.

Mr John is the second person from Swansea to have been named as among the thousands missing after the terrorist attacks.

Financier Catherine James, 37, also from Swansea, was working on the 100th floor of one of the towers when the attack occurred.

Thousands of people from around the world are still missing in the rubble of the collapsed symbol.

Representatives from financial companies which lost staff in the attacks will be present at the ceremony, which follows a recent service at the site in New York in October.

UK Culture Secretary Tessa Jowell said: "This will be a time for reflection and mourning across the country.

"We in the government and many relatives thought it was right to have an event at home in the UK, just for UK victims and something that would be organised after a little bit of time had passed."