English Heritage has hit back at claims that it has endorsed the controversial King Alfred redevelopment scheme.

Karis's managing director Josh Arghiros said last year that the public body had given its support to the £290 million Frank Gehry seafront development.

But in a letter to Brighton and Hove City Council released this week, Graham Steaggles, EH's historic area adviser, said that although it "broadly supports" the project it still has important concerns.

A new sports complex, shops and 751 homes are planned for the site of the crumbling leisure centre, which has been the subject of a series of failed development bids.

A recent poll revealed that two-thirds of the city supports the development but the scheme has also attracted much criticism from resident groups and councillors. Mr Steaggles also expressed surprised at Karis's assessment that English Heritage's remaining concerns were beyond its remit and subjective.

He said: "We must disagree with the applicant's view on our remit, while limited, the comments English Heritage have made relate to the possible impact of proposals directly or indirectly on the historic environment - the site is largely surrounded by conservation areas and lies opposite listed buildings.

"Indirectly there are also possible longer term impacts on Brighton and Hove and the well-being of its historic fabric and character. This is applicable to this scheme and others along the seafront, hence our comments on the relevant appearance of external elevations, public realm, pedestrian and traffic implications.

"Finally, the applicants statements appear to be concluding that a lack of objection is endorsement; and yes English Heritage are broadly in support of this scheme, but we must reiterate this support, as indicated in our letter, is qualified, and we would argue that a large set piece scheme such as this, in such a prominent position deserves considerable attention if its objectives and longevity are to be delivered.

Valerie Paynter, from Save Hove which is protesting against the scheme, said: "The letter makes it clear English Heritage are not happy and that they do not fully support it."

Councillor Averil Older, who is an opponent of the development, said: "English Heritage appear to have big concerns and are clearly rattled by Karis's publicity machine, stating that they have EH endorsement."

A Karis spokesman said it welcomed English Heritage's contribution and that although the body had raised issues about some details, it had nonetheless given its broad support.

He said: "The details in question refer to the durability of the materials, the number of balconies on the western elevation, the roof plant, details of the Juliet balconies, the eastern elevation and the works on the Kingsway.

"Karis Holdings has responded on all these issues in order to satisfy EH's concerns and welcomes further dialogue."

The scheme is set to be heard at a planning committee in the near future, but is currently being held up by a linked development of a new indoor bowls facility in Hove Park, The Droveway.