Sources close to the project said contractors and designers were under instructions to scale down their original designs in a bid to save money and ensure the £750m project is complete in time for its official opening in December.
A spokesman for New Millennium Experience Company denied that designers were being pressured into coming up with less expensive designs. However, the spokesman confirmed that many of the original specifications for the dome's 14 zones had been altered.
The spokesman said: "It's not the case that the design concepts have been scaled down. We always said there would be changes along the way from the concepts that were initially put forward. The content now is actually better that we had hoped for."
However, a project source said: "They have been desperate to scale down the specifications of the zones. They're continually asking designers to compromise their initial concepts to knock a few million off the cost of each zone.
"Time is an issue but I think it's cash constraints mostly. They're looking at the build costs and saying 'can you take out this bit and lose that bit?' The designers aren't happy because they feel they are having to compromise and ruin their original concepts."
The designers feel they are having to compromise and ruin their original concepts
The design changes are also thought to have caused confusion among contractors involved in the project. One insider said some contractors were still working to the original designs as new specifications had not yet been finalised for many of the zones.
The cost-cutting exercise is also thought to be behind the reason for Richard Rogers Partnership being asked to takeover one of the zones.
In March, Richard Rogers was handed design work on the Play Zone, which was originally carried out by London design company Park Avenue.
Richard Rogers declined to comment on the circumstances that led to its taking over the Play Zone, but it is understood that Park Avenue's original design was judged to be too expensive to build.
A spokesperson for Park Avenue, which is still involved in the project as designer for the Global Zone, said the company was unable to comment on the decision to award the Play Zone to Richard Rogers.