Bookseller Blackwell's is enmeshed in another family row after a move to sell some or all of its 64 bookshops.

An unnamed major family shareholder has called on the company's board -- headed by Philip Blackwell, great-grandson of the Oxford company's founder -- to obtain prior approval before a sale.

A spokesman for Blackwell's said a date for the meeting had not been set, but it would have to be called within 21 days. The news followed an announcement by the company that it is considering a number of approaches for its shops, which would be valued at up to £25m.

The shareholder tabled a resolution demanding that the board "obtain the prior approval for any sale or other disposal of the whole or any part of the company's retail business", but it is understood that the board would need to approve a sale in any case.

The Blackwell family is unhappy at the suggestion that they could be rebranded as student lifestyle outlets selling souvenirs and clothes.

The 10 family shareholders are also reluctant to sell the Broad Street shop, which opened in 1879.

Two years ago, the family was involved in a row over Blackwell Publishing, a separate company based in Cowley. Its chairman Nigel Blackwell wanted to keep it as an independent company, while his uncle and former chairman Toby Blackwell was pushing for a trade sale. As well as its flagship Oxford branch, which is among the largest bookshops in Europe, Blackwell's also owns Heffer's in Cambridge and James Thin in Edinburgh.

Last week, the company received offers from third parties for "some or all" of the shops. Chief executive Philip Blackwell said: "Blackwell's has long enjoyed the reputation of being the premier academic bookseller in the UK and we are determined that this should remain the case.

"However, given changing market dynamics and increasing consolidation, we now consider it appropriate to undertake a full review of the strategic options."