US President Barack Obama and German Chancellor Angela Merkel urged European countries to tackle their debt burdens with the support of the international community during a phone call today morning, dpa reported. "We agreed on the importance of a strong policy response by the affected countries and a strong financial response from the international community," Obama said in Washington. The call came as leaders of the 16-member eurozone were holding an emergency meeting in Brussels to discuss the debt crisis and the bailout of Greece's government, which sits at the epicentre of the turmoil. The German parliament voted earlier Friday to approve 22.4 billion euros (28.5 billion dollars) in aid for Greece, paving the way for a larger 110-billion-dollar bail-out by the EU and IMF to be approved at the Brussels summit later Friday. Obama said he "made clear that the United States supports these efforts and will continue to cooperate with European authorities and the IMF during this critical period." Treasury Secretary Timothy Geithner had also been on the phone in the morning with a number of his European counterparts, according to White House spokesman Robert Gibbs. US markets plunged more than 3 per cent on Thursday as Greek demonstrators took to the streets in violent protests against austerity measures. Investors are concerned the crisis could extend to other European powers like Portugal and Spain. US economic officials were working to ensure "what happens in Greece is not going to threaten the overall economic recovery," Gibbs said.