Following a heated exchange about Jowell's comments, DCMS sports chief Nicola Roche was forced to retract the allegations. Zaha, who worked on the scheme with S&P Architects, is understood to have threatened Jowell and her department with legal action before the letter was produced.
The document, dated 21 December 2005, represents an extraordinary climbdown for the minister, given the vehement nature of her earlier comments about the scheme.
'I have had to send the designers of the Olympic Aquatics Centre back to the drawing board because a change in the specification had almost doubled costs, which is simply unacceptable,' she told the Thames Gateway Forum on 24 November 2005.
Jowell continued: 'In our bid we pledged that the centre would cost £75 million, and that is what it will do. I will ensure that any potential overspend, no matter how small, is caught early and driven back down wherever possible.'