The British move comes as the United States throws a second lifeline to Citigroup and Bank of America, and considers ways to relieve banks of their troubled assets using hundreds of billions in new money from the Troubled Asset Relief Program, known as TARP. In Washington on Sunday, David Axelrod, a top adviser to President-elect Barack Obama, said that the second half of the $700 billion bailout fund, to be released after Mr. Obama takes office, must be administered in a way that will get “credit flowing again to businesses and families across the country. That hasn’t happened with the expenditure of the first $350 billion.”

Other European bailout plans are also coming together. The French president, Nicolas Sarkozy, and his finance minister, Christine Lagarde, will meet Tuesday with French bankers to press them into ease their lending restrictions.

“The banks must understand that the times have changed,” Ms. Lagarde said in an interview published Monday in a business daily, Les Échos. “The president was very clear: To benefit from a new capital injection, they will have to make precise commitments”  including giving up bonuses this year.

As if to illustrate the depths of the problem, Royal Bank of Scotland warned on Monday that it faced losses of up to £28 billion or $41 billion for 2008, a figure that would be a record for any British company. That includes as much as £20 billion of goodwill write-downs from the acquisition of a portion the financial giant, ABN-Amro. Royal Bank of Scotland’s shares fell nearly 67 percent Monday.

The downgrading of Spain’s sovereign debt  the second European country to suffer that fate in less than a week  added to the sense of urgency in Europe. Greece’s sovereign debt was cut last Wednesday, rekindling worries about what might happen to the euro zone as a whole if a member were to default on its public debt.