The General Assembly has admitted South Sudan as the 193rd member of the United Nations, sealing the new African country's independence after decades of conflict.
The assembly vote, by acclamation, followed South Sudan's independence proclamation in the capital Juba on Saturday, after its people voted in a January referendum to break away from Sudan - a decision accepted by Khartoum.
Applause broke out in the assembly as South Sudan became the first country to join the world body since Montenegro in 2006. The Security Council, which rules on all UN membership applications, had recommended the admission yesterday.
"Welcome, South Sudan. Welcome to the community of nations," UN secretary-general Ban Ki-moon said. Assembly president Joseph Deiss said it was a "historic and joyous moment."
The South Sudan flag - black, red and green stripes, overlaid with a blue triangle and gold star - was later hoisted outside the UN headquarters in New York.
South Sudan's vote for independence was held under the terms of a 2005 peace deal ending a 20-year war between north and south Sudan, in which more than 2 million people died.
Sudan - until now Africa's largest country - became independent in 1956 but was long plagued by conflict between its mainly Muslim Arabic-speaking north and its black African south, where many are Christian or follow traditional beliefs.
Presenting the admission resolution to the assembly, South African justice minister Jeff Radebe said South Sudan was an exception to Africa's practice of adhering to colonial borders and "in no way creates a precedent for separatist tendencies."
The new country will be one of the world's poorest and inherit a string of disputes with Khartoum. But representatives of the two countries pledged on Thursday to put the past behind them and resolve outstanding issues peacefully.
Continuing a show of graciousness by Khartoum over South Sudan's secession, Sudan's ambassador Daffa-Alla Elhag Ali Osman said the peoples of both countries would continue to be all Sudanese and members of one family.
"This is a new page and we hold out our hand to all," he told the assembly. "We and our brothers in South Sudan have left bitterness and the wounds of war behind us and we're looking to the future."
South Sudanese vice president Riek Machar paid tribute to Sudanese president Omar Hassan al-Bashir for his "wisdom" in signing the 2005 peace deal and for "courageously accepting the outcome of" the January referendum.
"It is our deepest and most sincere wish to resolve all outstanding matters between north and south safely and peacefully," he said. "We do not harbor bitterness towards our former compatriots."
Unresolved disputes between Juba and Khartoum include the exact borders between the two states, citizenship, and the sharing of oil resources.
Which country will own the border region of Abyei - where a 4,200-strong Ethiopian U.N. peacekeeping force is shortly to deploy - is still undecided and Khartoum's forces have been battling pro-southern fighters in Southern Kordofan, which is part of Sudan.
Despite having oil, South Sudan will need substantial foreign aid. UN chief Ban acknowledged this week that "on the day of its birth, South Sudan ranks at the bottom of almost all human development indicators."
Reuters