U.N. Secretary-General Ban Ki-moon has congratulated South Sudan on the first anniversary of its independence, saying the country's people have made “tremendous sacrifices” and can now “proudly walk the world stage.”

The head of the U.N. mission in South Sudan, Hilde Johnson, delivered Mr. Ban's remarks during a celebration Monday in South Sudan's capital, Juba. President Salva Kiir was also scheduled to speak at the event.

Mr. Ban cautioned that the country still faces many challenges, but said the United Nations will continue to support the government and work to help resolve all outstanding issues with neighboring Sudan.

South Sudan broke away from Sudan following a referendum that was part of a 2005 peace deal. The agreement ended a 21-year north-south civil war.