PHOTOS: Tenth Anniversary Of The London 7/7 Bombings

Britons have laid flowers at the sites of the 2005 London suicide bombings and held a nationwide minute of silence for the 52 victims on the tenth anniversary of the attacks.

Prime Minister David Cameron on Tuesday led the tributes by placing a wreath at a memorial in Hyde Park and petals were released from the dome of St Paul's Cathedral during a service there.

The Hyde Park ceremony began at exactly 8.50am local time - the time the first of four homegrown jihadists detonated his device on London's transport system on July 7, 2005.

"It's still raw 10 years on," said Mark, a 40-year-old train driver fighting back tears on the plaza outside King's Cross train station, near two of the four blast scenes.

"You see things you don't want to see again," he said, adding that he was on duty at the time and was involved in rescue operations.

Bouquets of flowers were laid in nearby Tavistock Square, on the spot where one of the bombers detonated his device on a red double-decker bus, killing 13 people.

"Our precious daughter Shyanu. When heaven took our angel back, they left two broken hearts," read one message left in memory of 30-year-old Shayanuja Parathasangary.

At Russell Square Underground station where a second device was detonated on a train, a tent was erected near the station entrance where mourners could sit and pay a silent tribute.

Spectators at the Wimbledon tennis tournament joined in the minute of silence, as did tourists outside St Paul's where families of the victims and survivors had gathered.

"Ten years on from the 7/7 London attacks, the threat from terrorism continues to be as real as it is deadly," Cameron said.

"The murder of 30 innocent Britons whilst holidaying in Tunisia is a brutal reminder of that fact. But we will never be cowed by terrorism."

The Britons were among 38 people killed when a gunman went on the rampage at a popular Tunisian beach resort on June 26, Britain's worst terror incident since the 2005 bombings.

Prince William joined the ceremony in Hyde Park where several survivors spoke of their experiences.

Emma Craig, 24, was just a schoolgirl on one of the trains targeted as she made her way to a work experience program.

"All of us lost our innocence on that day," she said.

"It might not have broken London but it broke some of us."

(Photos from Getty Images)