LONDON (AP) — The roller coaster ride continued for battered mortgage lender Northern Rock yesterday as its shares tumbled to an all-time low before some of those losses were pared when a potential buyer for the entire bank emerged.

Trading in the stock was temporarily suspended by the London Stock Exchange when shares tumbled 40 percent to 60 pence, valuing the company at just over £250 million ($515.3 million). Northern Rock was valued at £5.2 billion at its stock market peak in February.

The sales rush was spurred by comments from the company that prospective bids were well under the current share price and also followed a report that US private equity house Cerberus would not make an offer.

However, investors were heartened to learn another US private equity firm, J.C. Flowers, put in a bid for the entire company and that it would allow the bank with roots dating back to the 1850s to keep its name.

That contrasts with the partial bids put forward so far by Virgin Money and Olivant Advisors. A person close to the talks said the bid includes £15 billion ($30.9 million) in debt financing that will be used to pay down part of a loan from the Bank of England and an injection of just over £1 billion ($2.1 billion) in new equity.

That person, who was not authorised to speak publicly about the issue, asked not to be named.

The person said the Flowers plan is contingent on ongoing funding from the Bank of England from 2010, which in total should not exceed the £10 billion ($20.6 billion) remaining after the £15 billion ($30.9 billion) repayment.

Analysts have estimated that Northern Rock has so far borrowed about £24 billion ($49.2 billion) from the central bank under an emergency loan facility that was extended in September when the global credit crisis left the lender without funding from the short term money markets.

News of the approach saw Northern Rock's stock losses reduced to a 5.4 percent fall to 98.6 pence.

British Treasury Chief Alistair Darling, who has come under increasing pressure amid concerns that the virtual collapse of the lender will cost taxpayers, said on Monday that the government will ensure the "public interest is safeguarded" by exercising its right to veto a deal if necessary.

Darling said the government would "only support a proposal that protects the interest of the depositors and the taxpayers".

The Treasury also warned that the support it has provided so far, estimated by analysts to be worth around £24 billion ($49.2 billion), could represent state aid under EU rules and therefore may be illegal if continued beyond the allowed six months, which end in February.

Cerberus and Flowers declined to comment.