Euro zone crisis: Obama speaks to German Chancellor

US President Barack Obama had a telephonic talk with the German Chancellor Angela Merkel as European leaders prepared to meet again to hammer out an agreement to resolve the euro zone crisis that threatens to engulf other parts of the globe.

Obama and Merkel spoke this afternoon, continuing their ongoing consultations on the financial situation in the euro zone, the White House said in a statement.

"As before, the President expressed his appreciation for the efforts the Chancellor and other European leaders are making to resolve the crisis," it said.

"Both leaders agreed on the importance of a lasting and credible solution to the crisis, and agreed continue their close cooperation on these issues," the White House said.

The conversation came as US Treasury Secretary Timothy Geithner met with key eurozone officials ahead of a crucial European Union summit in Brussels.

Ahead of the summit, credit rating agency Standard and Poor's put a number of large European banks on review and placed the European Union on watch for a downgrade of its AAA rating.