Stricken British mortgage lender Northern Rock may have borrowed a further 2.3 billion pounds ($4.7 billion) from the Bank of England in the past week, according to BoE data, down from 2.9 billion the previous week.

The BoE's weekly accounts showed on Thursday that its other assets -- the category which would include the lender of last resort support to Northern Rock -- rose by 2.3 billion pounds and have risen by 12.9 billion in the last four weeks.

Northern Rock became Britain's biggest casualty of the credit crunch last month, when it saw a run on deposits after it was forced to seek an emergency funding line from the BoE.

It was handed a fresh lifeline by the UK government earlier this week, with guarantees for new retail deposits in the bank and extended funding arrangements with the BoE, winning time for the bank as it assesses options for its future.

In a statement on Thursday, the government said it would also compensate the central bank should it find itself out of pocket after providing emergency financing for Northern Rock -- even though the loans are secured against the bank's assets.

According to the Bank of England data, borrowing by the beleaguered mortgage bank has come down for two straight weeks, after a peak of 4.9 billion pounds.

I think 2.3 billion is still very disappointing, and presumably is why the (government) guarantee has been extended to new retail deposits this week, economist Simon Ward at fund manager New Star said.

The BoE and Northern Rock have declined to comment on how much the central bank has lent, but economists have pinpointed the other assets category of the BoE's weekly balance sheet data as the best guide.

Northern Rock's shares, down 60 percent since it was forced to seek emergency funding, have been increasingly volatile and were over 7 percent lower near the close on Thursday following a more than 32 percent jump on Wednesday after influential hedge fund SRM Global took an interest of over 4 percent in the stock.