When Sebastian Coe unveiled the logo for the 2012 Olympics in London yesterday he described it as an invitation for people everywhere to participate. Rarely, even in his glittering athletics career, can Lord Coe’s ambitions have been realised so spectacularly.

Within moments the first howls of dissent had registered in cyberspace. By lunchtime a petition had been posted calling on the Games’ organising committee “to scrap and change the ridiculous logo unveiled for the London 2012 Olympics” and by 7pm it had more than 8,000 signatures.

On the BBC website thousands mocked the design, comparing it to a disfigured swastika and a window that had had a football kicked through it. Others poured scorn on the £400,000 paid to a brand consultancy to produce it.

Instead of whetting the world’s appetite for “Everyone’s Games” as hoped, the Olympic organisers found themselves fighting a furious rearguard action in defence of their expensively acquired new brand identity.

Paul Deighton, the chief executive of London Organising Committee of the Olympic Games, said: “This is a bold logo. We were a bold bid and this will be a bold Games. We make no apology.”

No competition was held for the work.

The committee selected Wolff Olins, the brand consultancy which has previously produced logos for Sony Ericsson, Unilever and Macmillan Cancer Support.

Wolff Olins was briefed to take the Olympics away from its corporate image, to make it more “street” and less boardroom. Above all the consultancy was urged to reach out to a younger audience which has become steadily less interested in the Olympic movement over the past 20 years.

The rebranding exercise took more than a year and cost £400,000, which was met privately rather than through public funds, Mr Deighton said.

“This logo is going to be key to us raising money commercially. All our worldwide sponsors are ecstatic with it. The moment everybody in the team [organising the Games] saw the shape it was a unanimous decision to move on that basis.”

However an informed source told The Times last night that the logo had provoked disagreement among two leading figures involved with the Games.

Ken Livingstone, the Mayor of London, was said to have been “frozen out” of the discussion months ago because he clashed with Lord Coe over the design and was shown the final version only about a week ago, the source said. “He hated it.”

Mr Livingstone’s office declined to comment, but a spokeswoman for the committee said that Mr Livingstone or his officials had been consulted, along with other stakeholders.

The new logo, a bold jagged emblem based on the numbers “2012”, comes in a series of very bright shades of pink, blue, green and orange, in a modern take on the Olympic colours.

It is intended to be versatile, eye-catching and easily animated, and to look good on mobile phones and websites as well as more traditional media such as mugs, mascots and T-shirts.

The word “London” and the Olympic rings are included in the first two digits but there are no obvious visual references to London landmarks, unlike the last time the city hosted the Games when the Houses of Parliament featured on the 1948 Olympic logo.

Lord Coe, the London organising committee chairman, introduced the new logo yesterday with a dynamic presentation at the Roundhouse in North London, supported by sporting celebrities such as Dame Kelly Holmes and Denise Lewis, the athletes, Jose Mourinho, the Chelsea football manager, and Andy Murray, the tennis player.

There were shades of his call to arms in Singapore two years ago when he pledged to use the London Games to challenge young people to return to sport.

“London will be Everyone’s Games, everyone’s 2012,” he said. “This is the vision at the very heart of our brand. It will define the venues we build and the Games we hold and act as a reminder of our promise to use the Olympic spirit to inspire everyone and reach out to young people around the world. It is an invitation to take part and be involved.

“We believe we have got something that will live, something that will help us as we approach the Games, something with an international feel and something that will help us with business.”

Tony Blair said: “We want London 2012 not just to be about elite sporting success. When people see the new brand, we want them to be inspired to make a positive change in their life.”

This message will be repeated over the next three months when London 2012 hosts road-shows at 27 venues around the country.