Some of Britain's biggest banks are reportedly facing credit rating cuts as early as this evening in a move which will stretch lenders' already taut finances.
Royal Bank of Scotland, Lloyds Banking Group and Barclays are all in line for a downgrade by ratings agency Moody's over fears the eurozone crisis threatens their stability.
The move would ramp up bank's funding costs, which in turn could be passed on to the consumer in the form of higher mortgage rates and charges.
The cuts are part of a wider review by Moody's of the global banking sector that Sky News said is likely to be unveiled later after the US market closes.
The downgrades, which are expected to range in scope from one notch to three notches, will follow joint efforts by the Bank of England and Treasury to boost cash flows in Britain's banks through a multibillion pound cheap loan scheme.
The banking industry has been hit by higher funding costs as the eurozone troubles escalated and has been hoarding money for fear of another worrying phase in the crisis.
The Bank held its first auction under the new scheme yesterday, offering £5 billion in cheap loans with a rate of 0.75%, which was entirely taken up by the country's lenders.
Moody's, which previously warned in February that rating cuts were on the cards for Britain's banks, is likely to take a more pessimistic view on the creditworthiness of lenders in the wake of the eurozone crisis.
There is no certainty that the move will be unveiled and could be delayed. The agency has already downgraded major banks in several European countries, including Spain and Italy, adding to the funding difficulties some of the lenders are experiencing.
A cut last month by Moody's to the credit rating of Santander UK, the British arm of the Spanish lender, prompted fears for the safety of customers' deposits - although this was denied by the bank.