Northern Rock advisers have begun talks with "a number" of interested parties over rescue plans for the business.

The Newcastle-based mortgage bank, which has borrowed an estimated £24 billion in emergency fund-ing from the Bank of England since September, said the discussions were to "clarify" the proposals.

Northern Rock said: "The company is aware that all stakeholders want clarity on the outcome of the strategic review as soon as possible and is therefore progressing the process as quickly as possible."

It went on to remind all stakeholders that "there can be no certainty that the discussions with interested parties will lead to an investment in or offer for the company".

And it said that the existing deposit guarantee arrangement put in place by the Government and the revised facilities agreed with the Bank of England and announced on October 9 remained in place.

The company, whose advisers include investment banks Merrill Lynch and Citi, as well as private equity giant Blackstone, also confirmed it had received proposals involving an offer "materially below" the £409 million market price it commanded on Tuesday.

The news hit the group's share price, which was down by as much as 18 per cent in early trading yesterday as shareholders faced up to potential losses.

Shares later staged something of a rally to close 14 per cent down on the day at 83.90p - cutting its market capitalisation to about £357 million.

The approach is understood to be from private equity group JC Flowers, whose consortium is planning to pay off £15 billion in taxpayers' cash and clear the rest of the bank's debt burden by the end of 2010 if successful.

The New York-based firm is headed by Christopher Flowers who made his name with the rescue of the hedge fund Long-Term Capital in 2000.

Northern Rock was at the centre of the first run on a UK bank in nearly 150 years two months ago after the summer credit crunch caused soaring borrowing costs and crippled its business plan.

The beleaguered bank has pledged to find a way forward by February next year, although it expects to make an announcement on its future before then.

Other parties interested in the group include a Virgin-led consortium, which is looking to rebrand Northern Rock as part of the Virgin Money business, while private equity firm Cerberus has reportedly made an approach.

Olivant, an investment group headed by former Abbey chief executive Luqman Arnold, is also looking. Mr Arnold wants to take a minority stake and bring in a heavyweight management to revive the group's fortunes.

Chancellor Alistair Darling was forced to step in to guarantee savers' deposits to end the bank run and faced criticism in the Commons over his handling of the crisis this week.

Mr Darling has said that saving Northern Rock "was the right thing to do" and stressed that the Government will have the final say over any rescue plans. Northern Rock's woes began in the summer's financial turmoil, which froze the money markets where the bank borrows most of its cash for mortgage lending.

Banks fearful of exposure to losses on investments based on high-risk US mortgage debt became much more cautious about lending to each other.