The surprise announcement means that the 56-year-old will vacate the role a year before the end of his second four-year term expires in November 2013.

The former Conservative Sports Minister succeeded Sir Craig Reedie as BOA chairman in 2005 shortly after London won the bid to host the 2012 Olympics and Paralympics as he beat the 1968 Olympic 400-metre hurdles champion David Hemery by a vote of 28 to 15.

He was re-elected unopposed in 2009 but has confirmed he will leave the role just a day after the conclusion of the London 2012 Olympics where he helped steer Team GB to a record medal haul of 65 medals, 29 of them gold.

"Today the press will be looking forward to what lies beyond the Games: to the United Kingdom's sporting future and the delivery of a real London 2012 sports legacy," said Moynihan in a letter to the National Olympic Committee.

"In this context of looking forward, I will let them know that I intend to hand on the baton smoothly and securely to a successor chair.

"I have given this a great deal of thought and I strongly believe that this is the right time.

"A new chair must have the opportunity to play a central role in the future strategy and direction of the BOA henceforth, and he or she must be integrally involved in the preparations for Sochi (the 2014 Winter Games) which, after all, is only just over eighteen months away.

"It is for this reason that I have made my decision now on the timing of the election, to ensure as long a period as possible for my successor to become established in the role, ahead of the next Games."

David Hemery (far right) joins British Deputy Prime Minister Nick Clegg, vice-chairman of the British Olympic Association Albert Woods and Princess Anne to watch Team GB arrive at the Olympic Village ahead of London 2012

The election process for the new chairman will be decided at a BOA Board meeting next month, which Moynihan will chair, while the vote is almost certain to take place in November.

Hemery, who is now the BOA vice-chairman, will be the early favourite to succeed Moynihan while Richard Leman, the President of GB Hockey and a BOA board member, is also thought to be a serious contender.

"I will be working with the BOA Board to ensure a seamless and efficient handover to my successor, after which I will return to the business world, focusing in particular on the energy sector," continued Moynihan.

"I will continue to support the Government in the House of Lords and, as we face the challenge of how to harness the enormous public enthusiasm and momentum generated by these Games to the goal of delivering a genuine sports legacy for both Olympic and Paralympic sport, as well as non-Olympic sport and recreation, I will take every opportunity to campaign for the interests of our athletes across the spectrum, from school sport to high performance programmes."

Although Moynihan has been praised for overseeing an overhaul of the BOA aimed at preparing for London 2012, which proved successful at these Games, his time as chairman has not been without controversy.

Last year he was at the centre of a storm after causing a dispute with London 2012 which revolved around the Joint Marketing Agreement (JMA) for the Games and the funding of the Paralympics.

Moynihan was widely criticised as he called for more money for the Paralympics to be given to the BOA but the dispute was eventually resolved in April last year.

He also campaigned vigorously for drug cheats to have a lifetime ban from Team GB but failed in his bid earlier this year after going through the Court of Arbitration for Sport (CAS).

Colin Moynihan speaks at a Team GB London 2012 press conference

However, his chairmanship ends on a high note as Moynihan today received the Olympic Order of Merit from the International Olympic Committee (IOC), the highest award of the Olympic Movement.

"I want to close by saying that it has been a tremendous honour for me to have chaired the BOA during this unique and very special, once in a lifetime, period of preparing for and hosting a Home Games," he added in his letter.

"I have been proud and privileged to work alongside all of you and to share this journey with you to the destination of a remarkable and historic third Olympic Games in London.

"Above all, I am pleased that the athletes are now totally central to everything we do.

"The role I have played in the success of Team GB and in witnessing the creation of sporting history will remain one of the greatest experiences of my life, as I am sure it will of yours."

Contact the writer of this story at [email protected]