Northern Rock is expecting to receive as many as eight proposals – some priced “aggressively low” – for buying all or some of the stricken bank.

Northern Rock and its advisers Blackstone, Citigroup and Merrill Lynch have set today as the deadline for indicative proposals.

JC Flowers, Virgin Group and Cerberus are expected to put in proposals to buy the whole bank.

Some proposals are only for parts of the business rather than the whole bank, and although the official deadline is today, late proposals could still trickle in over the weekend.

It is understood that “one or two” banks from continental Europe and Asia are also looking at putting in proposals.

Shares in the bank, which have been incredibly volatile since it emerged that the Bank of England had offered emergency funds in August, fell 1.2p or nearly 1 per cent to 133½p in early trading on Friday.

Northern Rock may issue a statement detailing where it is in the auction process as early as next week. The sales memorandum used to sell the company suggests that even if Northern Rock were to be bought outright, the Bank of England may have to provide it with £6bn of support until 2010.

Some bidders are thought to have lodged low bids and are expecting the UK government to provide Northern Rock with some form of support after any takeover. The memorandum not only sets out a possible sale of the whole bank, but outlines two other options – splitting it up or selling off basic infrastructure such as branches and leaving some assets and liabilities behind for an orderly run-off.

However, it is thought that one or two of the bidders have come along with bank backers which are prepared to refund the Bank of England over a period of time if, for example, the government were to keep in place its guarantees for retail savers.

Such a proposal would be far more palatable to the government and the company than any bidder relying on sustained Bank of England support.

“The idea is that this reverts to the private sector as quickly as possible,” said a person familiar with the situation.

It is thought that Northern Rock has no plans to suspend its shares in spite of the huge volatility in the price, because it would “add to the crisis mentality” that continues to surround the company.

Alistair Darling, the UK finance minister, will next week make it clear that he has no prejudice against a private equity bid, insisting that his principal concern is “protecting the taxpayer” in any deal.

Mr Darling knows that a private equity sale could be politically awkward, particularly if it is underwritten – as expected – by taxpayer-backed loans and then subsequently sold on by “fat cat bosses” at a big profit.