ASUNCION (Reuters) - Spain and Portugal said on Saturday the euro zone's debt crisis is a global problem, calling on the United States and other G20 powers to help contain the fallout. Spanish Prime Minister Jose Luis Rodriguez Zapatero urged the G20 countries least affected by the crisis to provide "urgent stimulus plans" to shield the global economy. Europe's debt crisis looks set to dominate the summit of Group of 20 leading economies in France from November 3-4.