A report questioning the financing of the King Alfred redevelopment has come under fire from the site's developers.

The District Valuer's Office cast doubt on the financial viability of the £290 million Frank Gehry-designed King Alfred towers and leisure centre after publishing findings on Karis's costings for the scheme.

But Karis, the developer behind the plan, has hit back. It said the figures the report was based on were inaccurate and that new, more detailed and "more robust" costings had been evaluated which showed the plan was viable.

The accuracy and implications of the 30-page document published by the District valuer, a wing of the Inland Revenue, has been disputed by all sides of the political spectrum.

Meanwhile, the city council said there was "a difference between the district valuer's and developer's opinion of construction costs".

Karis released a statement yesterday stating: "The summary report was founded on figures supplied by Karis but used a general guide on building costs published by the Building Cost Information Service to estimate the construction costs.

"Karis, meanwhile, has taken more detailed costings produced by a team at Davis Langdon, the UK's largest cost consultancy, who have been working for two years on the scheme and have the advantage of the latest detailed Stage D design drawings.

"These figures are more robust and confirm the project is profitable."

In a response to the doubt cast on the figures it used in its report, the District Valuer's Office said any argument about their accuracy would be up to Brighton and Hove City Council to comment on.

The council said: "Given the unique nature of the scheme, it is not surprising there are differences in the analysis so far."