MANCHESTER, England - Prime Minister Theresa May joined Prince William at a memorial service on Tuesday to remember the 22 victims of a suicide bombing at a pop concert in Manchester a year ago, Britain's deadliest attack for 12 years.

Salman Abedi, a 22-year-old Briton born to Libyan parents, blew himself up in the foyer of the Manchester Arena in northern England at the end of a show by US singer Ariana Grande as the crowds began to leave.

His victims included seven children, the youngest aged just eight, while more than 500 were injured.

"Thinking of you all today and every day. I love you with all of me and am sending you all of the light and warmth I have to offer on this challenging day," Grande wrote on Twitter, including a bee emoticon, the symbol of Manchester.

On Tuesday, an hour-long service of commemoration was held at Manchester Cathedral while there was also a nationwide one-minute silence. William, Queen Elizabeth's grandson, delivered a Bible reading and met some of the bereaved families privately afterwards.

"The targeting of the young and innocent as they enjoyed a care free night out in the Manchester Arena on May 22, 2017, was an act of sickening cowardice," May wrote in an article for the Manchester Evening News newspaper.

"It was designed to strike at the heart of our values and our way of life, in one of our most vibrant cities, with the aim of breaking our resolve and dividing us. It failed."

In other events being held in the city, singers from local choirs, including the Manchester Survivors Choir made up of those caught up in the attack, will join together in the city for a mass singalong titled "Manchester Together - With One Voice".

It echoes a moment when crowds broke into an emotional chorus of "Don't Look Back in Anger" by Manchester rock group Oasis after a minute of silent tribute days after the bombing.

At the exact time the attack occurred, 10.31 pm, bells will also ring out across Manchester.

Britain is seeking the extradition of Abedi's brother Hashem from Libya over the attack, although the authorities do not believe a wider network was involved.

The Manchester bombing was the deadliest of five attacks in Britain last year blamed on militants which killed a total of 36 people.

Reuters