Washington - US President Barack Obama on Saturday emphasized the need for countries to work together to confront global challenges. He pointed to the economic crisis, terrorism, the environment and nuclear nonproliferation as issues that require international cooperation.

"These are challenges that no single nation, no matter how powerful, can confront alone," he said in his weekly radio address. "The United States must lead the way. But our best chance to solve these unprecedented problems comes from acting in concert with other nations."

He noted efforts last week at the Group of 20 (G20) meeting of leading and emerging economies to address the financial crisis and his travels throughout Europe, which also included a NATO summit, discussions with European leaders in Prague and a stop in Turkey.

"With all that is at stake today, we cannot afford to talk past one another. We can't afford to allow old differences to prevent us from making progress in areas of common concern. We can't afford to let walls of mistrust stand," he said.

"Instead, we have to find - and build on - our mutual interests. For it is only when people come together, and seek common ground, that some of that mistrust can begin to fade. And that is where progress begins."

Obama also sent holiday wishes to Jews celebrating Passover and Christians marking Easter and said the holidays offer a chance to reflect on obligations to others. (dpa)