The project was due for completion in September

In a statement, Mowlem said it has a fax from December 2001 saying the design changes were agreed by designers Grimshaw and the city council.

Mowlem has been caught in a legal row with Bath and North East Somerset Council (Banes) about the project.

But it now claims it could have the project open within six months.

The company has offered to take over the design and build of the centre altogether - for a fixed price.

A Banes spokesman said the council had only just received Mowlem's statement and would need time to consider it.

In a statement, the firm said: "At a time when Banes is voting through millions of pounds for a legal battle reaching into 2006 and beyond... but is still unable to give any opening date for the Spa, Mowlem will guarantee to open the spa within six months."

Declined or ignored

It says its plans would stop the council spending any more taxpayers' money on the project.

Mowlem says the offers have so far been "declined or ignored".

On the subject of the waterproofing, the statement went on to say the design was changed "from a perfectly good and workable" one to "the failed design, in an attempt to save money".

Mowlem says this issue has been the main problem which has delayed the opening.

The contractor claims to have raised the issue "in detail" in October 2003 before Grimshaw finally investigated the issue in August 2004.

Frustrated

Paul Crossley, Leader of Bath & North East Somerset Council said: "We have been in correspondence with Mowlem regarding the potential of finding a way forward that will complete the project.

"It is a complex issue and so needs to be carefully considered by all sides. We will do this in private not via the press.

"The Council and the Millennium Commission want the building completed and open.