About half the tickets for the men's 100m final at the London 2012 Olympics are to be sold to the British public, Games organisers have said.
Of the 72,500 seats for the event on 5 August, 58,500 tickets were to be sold and of those only 50% were to be made available to UK applicants.
Locog said around 20,000 of those tickets have already been bought.
Meanwhile Locog chair Seb Coe defended the transparency of the ticketing process at a London Assembly meeting.
He said to give more information now would be "dangerously misleading."
During the question-and-answer session at the Assembly, Lord Coe was accused of being "obsessed with secrecy" over the running of the London 2012 Games, including the controversial issue of tickets.
Locog has been under pressure in recent weeks over a lack of transparency in the ticketing process, with calls for them to provide a detailed breakdown of how many tickets have been sold at what price for each event.
Assembly member Dee Doocey said while Locog was doing a "superb job" she was "endlessly frustrated at excessive secrecy" surrounding ticket sales.
She said: "There is nothing at all to stop you from publishing it if you have got nothing to hide. You are not transparent."
But Lord Coe insisted: "I am sorry but we are being entirely transparent here.
"We are determined to get through this ticket process in the way we have outlined to you."
There are only 72,500 of the 80,000 seats in the Stadium available for the 100m final because of big screens at each end of the venue.
A further 17,000 seats are taken out of the equation through a mix of accredited media, sports representatives, athletes and because views are obstructed.
London 2012 chief executive Paul Deighton said: "On the narrowest definition, 50% of the tickets for the 100m final will be distributed through the broad approach to selling tickets to the UK public."
He also said that they would not be using the unprecedented demand for tickets as an excuse to increase prices for those yet to be put on general sale.
Earlier it was revealed that London 2012 organisers have set aside a special allocation of Olympic tickets in an attempt to ease concerns that local sports clubs and volunteers might miss out in the public ballot.
The BBC understands 81,000 - just under 1% of the total number of tickets - have been handed to 33 Olympic sports.
The tickets are not from the 6.6m tranche being offered for general sale.
Instead, they come from the 2.2m set aside for VIPs, sponsors and the so-called Olympic family.
It comes amid criticism that Locog has failed to make enough tickets available for grassroots clubs and their members.
With a million extra tickets due to be made available in the last round of sales in April, Locog is aware that many clubs and volunteers may have missed their chance to secure tickets.