Several of London's successful 2012 bid team returned home from Singapore this morning struggling to come to terms with their emotions after yesterday's events in the capital.

The terrorist attacks, which have so far claimed 52 lives and injured more than 700 people, came less than 24 hours after London had dramatically won the right to host the 2012 Olympic Games.

All of the team's home-coming celebrations were cancelled and British Olympic heroes Sir Steven Redgrave, Denise Lewis, Daley Thompson and Colin Jackson walked through the arrivals hall in a sombre mood.

Tessa Jowell, the Culture Secretary and a member of the bid team, said last night: "The plans for celebrations have been cancelled. They would be completely inappropriate in the light of this appalling tragedy."

Redgrave vowed security will not be an issue at the London games and insisted that the budget already takes major security measures into account. But it was all a bit too early for a debrief from the bid team, who were recovering from the celebration parties when news of the bomb blasts reached Singapore.

"It was a very strange flight. Fortunately it was overnight but I didn't get much sleep," Redgrave, the five-times gold medal-winning rower, said. "It's been pretty incredible. It's a feeling of devastation, my emotions over the last 24 hours have gone from one extreme to another.

"Security is a big issue whatever the situation is. All the bid cities are on the highest priority for security and it was always in the budget."

Denise Lewis, the gold medal-winning heptathlete, spoke of her "devastation" at the news and Simon Clegg, chief executive of the British Olympic Association, expressed his heartache over the London bomb blasts.

"It's very difficult time. Our hearts are with the victims and their families," he said.

Several other members of the bid team remain in Singapore after their flight was cancelled due to mechanical failure last night.

Most of them returned to hotels but Ken Livingstone, the mayor of London, Tessa Jowell, the Culture Secretary, Lord Coe, the London 2012 chairman, and Richard Caborn, the Sports Minister, were moved on to another flight.

Earlier, Olympic officials in Singapore observed a moment's silence in memory of those killed in London at the start of a meeting. The 115 members of the International Olympic Committee were also told by Britain's Olympic chief Craig Reedie that the attacks would not stop London hosting "an excellent Games".

Jacques Rogge, the IOC president who has sent letters of condolence to Tony Blair and Livingstone, told members: "We begin with a sad and painful issue. The IOC was appalled by the barbaric attack in the heart of London.

"This tragic act has sadly proved that there is no safe haven on this earth and that security must remain the first priority whenever Olympic Games are staged. I ask you to stand in honour of the victims."

Reedie, chairman of the British Olympic Association, said: "I can assure you that when we return to London these terrible acts will in no way reduce our resolve to run excellent Olympic Games in 2012. The worst thing to do is to concede anything to these people."

Henri Serandour, head of the French Olympic committee and one of the leaders of the Paris bid, added: "Today we all feel like Londoners. It's terrible we are all in mourning."