The full range of ticket prices for the 2012 Olympics in London will be announced on Friday.
But despite the promise to "make tickets affordable to all", organisers say they may no longer be able to honour a bid pledge to price some tickets at £15.
The removal of baseball and softball from the Olympic roster has been blamed for the inability to keep the promise.
More than 1.4 million people have registered their interest in tickets, which will go on sale from early 2011.
In excess of eight million tickets will be sold in total, covering the preliminary and final events of all 26 Olympic sports.
It was initially announced that, in addition to £15 tickets, around half would be priced at £30 or less.
It was envisaged that the bulk of tickets in the cheapest price bands would be for low-profile events such as baseball and softball, for which there was little demand.
However, the International Olympic Committee voted in 2005 to remove both sports from the programme for London 2012.