European leaders have started a two-day summit in Brussels in the latest effort to resolve the continent’s debt crisis and save the euro.

Some officials have described the European summit as a moment of reckoning for the common currency, under siege by Europe’s burgeoning debt crisis. But before the meeting opened Thursday night, there remained a divergence of opinion on exactly how to resolve the two-year debt contagion that threatens the stability of the world economy.

U.S. President Barack Obama told reporters in Washington that Europe is prosperous enough to resolve the debt crisis if its leaders have the political will to act.

The economy in the 17-nation bloc that uses the euro has all but stalled, with some analysts saying it has already dipped into a recession. The European Central Bank took a modest step ahead of the summit to boost lending, trimming its prime interest rate a quarter percentage point to one percent, the second cut in two months.

But stocks slid on European and U.S. exchanges after the bank’s president, Mario Draghi, dampened speculation that the central bank would increase its purchase of the debt of European governments as one way to cut their borrowing costs. A European regulator said the continent’s banks need to raise nearly $154 billion to cover possible losses on government securities they hold.

German Chancellor Angela Merkel and French President Nicolas Sarkozy are calling for the eurozone nations to curb excessive spending and impose strict penalties on violators. Their plan would also create a unified corporate tax rate and a new financial transaction tax.

Mr. Sarkozy said an agreement is essential.

before a deal is reached. Another senior official was quoted as saying that some countries “have not understood the seriousness of the situation.

Fears that Europe’s debt crisis could spark additional problems have sent jitters through the global financial markets and have prompted warnings from several top credit rating agencies.

Britain, which has its own currency , has indicated that it may not be willing to sign on to new EU treaty provisions. Prime Minister David Cameron said earlier this week that he will defend Britain’s financial interests at the summit.