Opponents say that light would be limited in the Edward VII galleries

A plan by the British Museum to build a £130 million exhibition centre in its northwest corner has provoked anger from heritage groups that claim it will destroy some of the 19th-century building’s most beautiful period details and vistas.

The ambitious scheme for the rear of the building in Bloomsbury, Central London, would provide 17,000 square metres (183,000 sq ft) for shows and conservation.

The museum has become the country’s most popular cultural attraction drawing more than six million visitors last year. It claims that with more space it could have accommodated “many times” more than the 160,000 paying visitors who enjoyed its recent Michelangelo exhibition.

It has commissioned Lord Rogers of Riverside to design a series of pavilions to replace the British Library’s former offices in Montague Place, but heritage groups say that the modern design will have a detrimental impact on Robert Smirke’s original building as well as its views over Georgian London.

Bill Reed, an architect and chairman of the Bloomsbury Conservation Area Advisory Committee (BCAAC), dismissed the redevelopment as “needlessly expansive and expensive”.

John Martin Robinson, vice-chairman of the Georgian Group, said he feared that a building making a modern statement would “seriously detract from the conservation area and the adjoining listed buildings”.

Hero Granger-Taylor, an archaeologist and member of the Camden Civic Society, said: “This doesn’t respect the existing building at all.”

They are particularly worried about how the scheme would impinge on the imposing marble staircase leading from the back of the building, the King Edward VII galleries and the Arched Room, a “hidden gem”. The proposals include building around the Arched Room, just as Lord Foster built around the Round Reading Room when he redeveloped the Great Court, which sparked controversy eight years ago.

The campaigners also fear that there would be a restriction of natural light into the Arched Room and the Edward VII galleries. They dismiss the museum’s argument that some of the windows need to have opaque glass for conservation reasons. They also believe that the existing views from the building, on to Grade I listed houses on Bedford Square will be harmed.

Tony Tugnutt, a design and planning consultant and former chairman of BCAAC, said: “Hidden treasures will be totally entombed by Lord Rogers’s building. It depresses me that architects cannot respect other architects’ work.”

The Bloomsbury Conservation Society wrote to the museum: “While we accept that the museum needs more space, and agree that the northwest corner is a suitable location for development, unfortunately . . . the solution as it currently stands is a missed opportunity that blights the existing buildings.”

Mr Reed said that Rogers Stirk Harbour & Partners, Lord Rogers’s firm, has “a successful track record of certain building types such as airports – but they are not the obvious choice . . . for a sensitive site . . . involving a Grade I monument in an outstanding conservation area”.

He said that sections through the pavilions resembled hulks in a dry dock that were “more to do with the architect’s current design obsessions than any unique solution specifically tailored for the British Museum”.

The museum hopes to open the new exhibition centre by 2011, subject to planning permission being granted by Camden Council.

Graham Stirk, project director for the architect, said that a planning application had not yet been submitted, and “we are still in the process of detailed consultation with a wide range of national and local organisations”. Although he claimed that the proposals “have evolved considerably”, heritage groups who saw the plans this month said that there was little regard to their criticisms and they detected only minor changes.

A spokeswoman for the British Museum said: “The northwest development will not impact on the galleries. A modern design doesn’t detract from the historic vista.”