September 11 attacks: Victims' families gather at Ground Zero to mark 20th anniversary of 9/11

ITV News US Correspondent reports on an emotional day from New York City

US families who lost loved ones in the 9/11 attacks have come together to pay tribute to them on the 20th anniversary of the tragedy.

Cities across the world will today fall silent to remember the 2,977 people whose lives were claimed on the morning of September 11, 2001 in the most devastating terror attacks in US history.

US president Joe Biden was joined by former presidents Barack Obama and Bill Clinton and a crowd of victims’ relatives and first responders for the ceremony at the 9/11 memorial plaza in New York City.

The memorial stands where the the World Trade Centre’s twin towers were rammed and felled by hijacked planes.

Observances are also planned at the the two other sites where the 9/11 conspirators crashed the jets: the Pentagon, and a field near Shanksville, Pennsylvania. Mr Biden is scheduled to pay respects at all three sites.

The anniversary arrives under the shadow of the coronavirus pandemic and the US withdrawal from Afghanistan – now ruled by the same militants who gave safe haven to the 9/11 plotters.

Six moments of silence marked the times when each of the World Trade Center towers was struck, when each fell, and the time corresponding to the attack at the Pentagon, and the crash of the US Flight 93 in Pennsylvania.

Ceremonies have also taken place at the Pentagon and in Pennsylvania where flight 93 came down after passengers on the plane fought back against the terrorists.

It takes three hours to read the names of the dead.

Earlier in the UK, the Queen and Prime Minister Boris Johnson were among those to send messages of support to allies in the US and those on home soil whose lives were changed forever on the morning of September 11 two decades ago.

A remembrance event at the Olympic Park in east London saw Mr Johnson say in a televised address that recent events in Afghanistan "will only strengthen our determination to remember those who were taken from us".

At Memorial Garden in Grosvenor Square, London, a private Special Service of Remembrance is being held by the September 11 UK Families Support Group.

Bereaved families read out the names of the 67 Britons who lost their lives in the attacks, as well as holding a minute's silence, before white roses were laid on the inscription stone within the garden.

After sunset, LED candles will be lit in memory of those who died, which will be open to the public.

At Windsor Castle, members of the military played the US national anthem at the Guard Change, watched over by delegates from the American embassy, and a silence was held to reflect on all affected by the tragedy.

The US national anthem is played during the Guard Change at Windsor Castle

In a video address shown at London's Olympic Park today, Mr Johnson said: “Twenty years ago, September 11, 2001 became, in President Roosevelt’s words after Pearl Harbour, a ‘date which will live in infamy.' “On a crystal clear morning, terrorists attacked the United States with the simple goal of killing or maiming as many human beings as possible, and by inflicting such bloodshed in the world’s greatest democracy, they tried to destroy the faith of free peoples everywhere in the open societies which terrorists despise and which we cherish.

“And it is precisely because of the openness and tolerance of the United States that people of almost every nationality and religion were among the 2,977 murdered on that day, including 67 Britons, each of them a symbol of the eternal friendship between the United Kingdom and the United States.

“But while the terrorists imposed their burden of grief and suffering, and while the threat persists today, we can now say with the perspective of 20 years that they failed to shake our belief in freedom and democracy; they failed to drive our nations apart, or cause us to abandon our values, or to live in permanent fear.

“The fact that we are coming together today – in sorrow but also in faith and resolve – demonstrates the failure of terrorism and the strength of the bonds between us. “Recent events in Afghanistan only strengthen our determination to remember those who were taken from us, cherish the survivors and those who still grieve and hold fast to our belief in liberty and democracy, which will always prevail over every foe.”

Ahead of the commemorations, the Queen sent a message to Mr Biden, saying her thoughts are with all the victims, survivors, first responders and their families.

“As we mark the 20th anniversary of the terrible attacks on September 11 2001, my thoughts and prayers — and those of my family and the entire nation — remain with the victims, survivors and families affected, as well as the first responders and rescue workers called to duty," the message read.

“My visit to the site of the World Trade Centre in 2010 is held fast in my memory. It reminds me that as we honour those from many nations, faiths and backgrounds who lost their lives, we also pay tribute to the resilience and determination of the communities who joined together to rebuild.”

London Mayor Sadiq Khan said that the attacks "changed our world forever".

“Today, we remember the innocent people who lost their lives – including the 67 Britons, many of whom were Londoners," he added.

“Our values of freedom, tolerance and respect will always, always prevail. Hate will never win.”