LONDON — Families of British victims of the September 11 attacks on the United States attended memorial services in London on Sunday to mark the 10th anniversary of the atrocity.

Around 2,000 people gathered at St. Paul's Cathedral to remember those killed in the 2001 attacks, who included 67 Britons.

Representatives of the fire, police and ambulance services were also present at the service, which was one of a series of memorial events taking place in Britain throughout the day.

"We gather in this cathedral today to remember before God all who died in the atrocities in New York, Washington and Pennsylvania 10 years ago and to pray with those whose lives were changed forever that day," said Reverend Graeme Paul Knowles, the dean of St. Paul's.

Among those at the service was Courtney Cowart, who survived the attacks despite being buried under rubble when the north tower of the World Trade Centre collapsed.

Prayers were led by people who lost loved ones in 9/11, including Angela Ridge, sister of broker Robert Eaton, and Jim Cudmore, father of advertising executive Neil Cudmore.

Earlier, the solemn day of remembrance got under way with a service at Grosvenor Chapel in central London, which has strong ties to the nearby US embassy and was a place of worship for American soldiers during World War II.

The centrepiece of the service was the lighting of a candle by deputy US ambassador to Britain, Barbara Stephenson.

Canon Jim Rosenthal, who led the service, said the 9/11 attacks knew "no race, creed, gender, age or status".

"Remembering such horrific scenes is not easy," he said.

"But remembrance is not static -- it's a constantly growing and evolving action which gives us the opportunity to take hold of the past and transform it to reach out with grace, understanding and healing."

US President Barack Obama, due to attend ceremonies marking 9/11 in the United States, praised the response of Britons in the immediate aftermath of the attacks.

"Those of us in the United States will never forget how the people of Britain stood with us in solidarity in candlelight vigils and among the sea of flowers at our embassy in London," Obama wrote in the Sunday Mirror newspaper.

The main 9/11 service in Britain takes place later at Grosvenor Square memorial garden in the capital.

British Foreign Secretary William Hague meanwhile said that Al-Qaeda, which carried out the attacks, was "weaker than at any time in the decade since 9/11".

"Political progress through peaceful protest in the Middle East and North Africa has shown (Al-Qaeda) to be increasingly irrelevant to the future," he said in a statement.

In the United States, Obama and his predecessor George W. Bush were due to attend ceremonies at the site of the destroyed World Trade twin towers in New York, with Obama also flying to 9/11's other crash sites in Pennsylvania and at the Pentagon.

Almost 3,000 people were killed that day in the worst attacks on American soil.