The Sky News reported, the Queen has paid tribute to the “resilience and determination” of 9/11 survivors, as Boris Johnson said the terrorists had “failed to shake our belief in freedom and democracy”.
In a tribute at Windsor Castle, the American anthem and other songs were played by the Band of the Welsh Guards in front of the acting US ambassador.
Mr Johnson, who was born in New York, said in a recorded message, the terrorists had “tried to destroy the faith of free peoples everywhere in the open societies which terrorists despise and which we cherish”.
The Sky News said, the Queen also sent a message to President Joe Biden.
She said: “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.
“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.”
The Sky News added, Archbishop of Canterbury Justin Welby said it was “still hard to articulate the loss that terrible day brought”.
Writing on Twitter, he said: “Today we pray for all those affected by terror and violence. May God guide us together towards the peace offered by the crucified and resurrected Christ.”
Labour leader Sir Keir Starmer also paid tribute and said how the “consequences of the 9/11 attacks are still being felt to this day – the tragedy is still so raw”.
He said: “We show support to our American friends as they mark this difficult time in their history.
“And we remember those in all corners of the world who have lost their lives to terror. They will always be in our hearts …and our memories.”