The motto for the London Olympics has been revealed as "Inspire a generation" as events are held to mark the 100-day countdown to the opening ceremony, BBC News reported.

London 2012 chairman Seb Coe was at the unveiling of a giant set of Olympic rings, made up of 20,000 flowers, at Kew Gardens in west London.

He said: "Expectations are high and we won't disappoint."

Organisers also said the Red Arrows will perform flypasts across the UK to mark the opening ceremony on 27 July.

The world-famous RAF aerobatic display team will fly in Big Battle formation across Belfast, Cardiff, Edinburgh and London to herald the Games, Locog said.

Announcing the motto, Lord Coe said: "It is everything we have been saying since we have started this extraordinary journey.

"It is the heartbeat, the very DNA of this organisation and a rallying cry for the athletes to come to the UK to perform at their very best and inspire the world."

International Olympic Committee president Jacques Rogge said he was confident London would meet the expectations of the world.

He said: "Around the world, the excitement is growing and expectations are high but I am confident that Britain and London will deliver a great sporting event and a warm welcome too."