World leaders are sending their congratulations to U.S. President Barack Obama, who won a second term Tuesday in a tightly contested race with challenger Mitt Romney.

U.N. Secretary-General Ban Ki-moon said he “warmly congratulates” Mr. Obama and looks forward to continuing to work together “in the spirit of the enduring partnership between the United States and the United Nations.”

British Prime Minister David Cameron said he looked forward to continued cooperation with Mr. Obama. He said the “appalling” events in Syria make clear Britain and the United States need to do more to try to resolve the crisis.

French President Francois Hollande told Mr. Obama his re-election was a “clear choice” in favor of an America that is “open, unified and completely engaged” globally.

China's Foreign Ministry said President Hu Jintao and his soon-to-be successor, Vice President Xi Jinping, were looking forward to working with Mr. Obama.

Israeli Prime Minister Benjamin Netanyahu said the U.S.-Israeli strategic alliance is stronger than ever and he will continue to work with President Obama. Mr. Netanyahu is a longtime friend of Mr. Romney.

Russian President Vladimir Putin sent a telegram to Mr. Obama with his congratulations, a spokesman said, adding the Kremlin leader received the U.S. election news “very positively.”

Sudan welcomed Mr. Obama's re-election and called for better relations. In a foreign ministry statement, the government called for “serious and responsible dialogue” and a removal of what it called “unjust unilateral economic sanctions.”

A spokesman for Pope Benedict said the pontiff expressed hope that U.S. ideals of liberty and justice “would continue to shine.”

The Dalai Lama, Tibet's spiritual leader, thanked Mr. Obama for his “steady encouragement” of Tibet's efforts to find a peaceful solution to its problems.

NATO Secretary General Anders Fogh Rasmussen told Mr. Obama he had demonstrated outstanding leadership in maintaining the “vital bond” between Europe and North America.

In Kenya, home of Mr. Obama's father, both national leaders praised the president's re-election. President Mwai Kibaki said it is confirmation of the American people's confidence in their leader. Prime Minister Raila Odinga said the election result will rekindle faith in democracy worldwide, and especially in Africa.

Mr. Obama's paternal grandmother lives in the Kenyan village of Kogelo, where she and other villagers celebrated the election's outcome. She told reporters she believes her grandson was re-elected because he has the capacity to love other people. And, as any grandmother would ask of her grandson, she implored Mr. Obama to do his best at his job.