Northern Rock has further increased the scale of its borrowing from the Bank of England, suggesting, according to one commentator, there has been a larger withdrawal by retail investors than previously thought.

The Newcastle-based lender borrowed a further £4.7bn ($9.5bn) from the Bank last week, it emerged on Thursday, taking the total to about £21bn. Six weeks after Northern Rock first went to the Bank for support as lender of last resort, its weekly borrowing has climbed from £3bn in the week to October 17 and £2.3bn the week before. The figures were revealed in the weekly publication of the central bank’s balance sheet.