Shortly after Benjamin Henry Blackwell opened his 12ft-square bookshop in Oxford, a reviewer wrote: "Those who came in from the noisy, cobbled street found quiet and an invitation, not so much spoken as conveyed by the friendly spirit of the bookseller, to scrutinise and handle the books without obligation to buy."

Shortly after Benjamin Henry Blackwell opened his 12ft-square bookshop in Oxford, a reviewer wrote: "Those who came in from the noisy, cobbled street found quiet and an invitation, not so much spoken as conveyed by the friendly spirit of the bookseller, to scrutinise and handle the books without obligation to buy."

For 125 years this genteel "gown not town" approach to bookselling has sustained the Blackwell's academic bookshop empire strung across Britain's seats of learning from Exeter to Aberdeen.

But yesterday the Oxford-based company finally surrendered to the harsh realities of modern retailing when it announced that it was considering the sale of "some or all" of its 61 stores in the face of fierce competition from the internet.

Managers at the family-owned firm said they had brought in a firm of City consultants, BDO Stoy Hayward, to review its network of outlets after it received at least three approaches from buyers interested in acquiring the chain, which has been valued at between £15m and £25m.

The favourite bookseller of generations of bicycling dons and budget-conscious students, whose publishing arm launched the careers of literary figures including Graham Greene and J R R Tolkien, insisted the sale of its stores was "just one option" among others which include a joint venture with a larger bookseller. But Blackwell's admitted the rise of online retailers such as Amazon and the increased use of the internet by students to source their research material, more often than not for free, has transformed the niche market it once dominated.

Philip Blackwell, the chairman, chief executive and great-grandson of Benjamin Henry Blackwell, said: "Given the changing market dynamics, we now consider it appropriate to undertaken a review of the strategic options for the business."

The decision to consider bids for the shops comes after three turbulent years within the Blackwell dynasty, the descendants of Benjamin Henry, who set up his tiny Oxford store within 100 yards of the Bodleian Library.

The company, which is owned by 10 family shareholders, was drawn into a public dispute two years ago over plans to sell its lucrative publishing arm for £300m. It was eventually turned into a separate company still owned by the family.

Sources insisted yesterday that the latest move was not linked to previous disputes and had the full backing of Blackwell's board. The review results will be announced in the new year.

The retailer, which employs 600 people and was the first in Britain to offer an online bookshop, had sales of £68m last year at its stores in locations including Bristol, Cardiff, Edinburgh, Cambridge, Manchester and Leeds. But after a series of buy ups by rival retailers it is now dwarfed by its competitors in Britain's £2.4bn book market.

Despite the internet accounting for less than 5 per cent of all book sales, the turnover of Amazon, the market leader, is far higher than Blackwell's, with estimated sales last year of £250m, including non-book items such as DVDs.

Smaller retailers and publishers have also blamed the end of the net book agreement - which allowed sellers to charge less than the recommended price - for increasing the pressure on their sales.

Those fearing that an eventual sale will lead to disposal of the company's founding store in Oxford can rest easy. The shop, which has expanded to a sprawling outlet owned by a trust that includes the Bodleian, Trinity College and the family shareholders, is understood to be extremely unlikely to be offered to bidders.