Plans for the London Olympics 2012 aquatic centre have been rejected for going two times over budget.
Olympics chiefs say they will stick with architect Zaha Hadid, but she has been ordered to bring costs back in line with the original £75m estimate.
"I sent the designers back to the drawing board because a specification change had almost doubled costs," said Olympic minister Tessa Jowell.
Hadid confirmed that the aquatic centre would be delivered on budget.
The original plans were for a 20,000-seat arena with two 50m swimming pools and a diving pool, but it is thought the seating may have to be reduced to 10,000 in order to keep to the original £75m plans.
"In our bid we pledged that the centre would cost £75m and that is precisely what it will do, with appropriate allowance for inflation," Jowell told Construction News.
"I cannot give anyone a complete assurance that costs for the 2012 Games will not rise.
"But what I will do is be absolutely ruthless in ensuring that any potential overspend, no matter how small, is caught early and driven back down wherever possible."