Ticket prices for 2012 will exceed bottom-line pledge

London 2012 organisers insist tickets for the Olympics will be "highly affordable", but admit they cannot guarantee to honour their initial pledge to make the cheapest available for just £15.

When the detailed bid for the Games was launched by the London 2012 chairman Lord Coe in November 2004, he said ticket prices would "start at £15 and over half of them are £30 or less and the prices include free transport". Now, with three years to go to the opening ceremony, organisers say the 2004 figures were just "indicative" and were based on dollars – the exchange rate is now different – and when baseball and softball were among the events. The lowest-priced ticket for 2012 has yet to be determined, a spokeswoman confirmed.

Paul Deighton, chief executive of the London organising committee, said: "It was all in dollars which was a bit confusing and at bid time we had both softball and baseball, which would have been a very significant number of relatively cheap tickets. The principle still applies that a very significant chunk of our tickets will be highly affordable so we can get families there. This is the strategy we are working on now and will be finished in 2010."

Asked whether he could say what the cheapest would be, Deighton replied: "Not yet." But he added: "A very significant proportion of the nine million tickets will be priced so they are very attractive." Deighton said they would have "a close look" to see whether the newly appointed ticket handler Ticketmaster would want to charge administration fees.

Meanwhile, the final position of the cauldron which will contain the Olympic flame is still being debated. There is the potential for it to be situated on the roof of the stadium, as it was in Beijing, but another proposal is for it to be located outside the venue, though on top of a large tower so it is still visible by those in the seats. London leaders are keen on finding a solution that will leave a meaningful legacy beyond 2012, making it more likely it will be outside the stadium.

The other outstanding decisions regarding the venues for shooting, boxing, badminton and volleyball will be made before the end of the year, Deighton said. Woolwich barracks has been earmarked for shooting despite opposition from the sport, with Barking as an alternative.

Organisers also want boxing to move to Wembley Arena to free up space in the ExCel arena for badminton and volleyball, so they do not have to build a £40m temporary venue at North Greenwich.

Deighton said: "Woolwich is the shooting venue, but Barking is a back-up venue just in case the constraints of working with a pretty tight site proved too challenging. We will certainly have made the decision by the end of the year."

In relation to boxing, he added: "The objective is to try avoiding building new or temporary venues if we can avoid it and find a smarter way of using other venues and finding the cheapest way to do it.

"One of the considerations in where we end up will be the impact on the athletes for whichever sports we look at, whether it's travel time or the venue they end up performing in."